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Subject: [FAQ] Aquaria: Beginning Fishkeeping
This article was archived around: Thu, 13 Jan 2000 08:03:09 GMT
* This is only a text dump of part of the Aquaria FAQs. *
* The web "original" may be more current, is navigatable hypertext, *
* and contains enhanced content not available in this posted version! *
* http://faq.thekrib.com or http://www.actwin.com/fish/mirror *
FAQ: Beginning Fishkeeping
contributed by Thomas Narten
Welcome to the wonderful world of aquariums. This FAQ provides advice
and guidance to help insure success in your endeavor. Though this
document is designed for a first freshwater aquarium (saltwater
people: make sure to read the SALTWATER BEGINNER FAQ), there is much
information applicable to both freshwater and saltwater aquaria.
This FAQ is a work in progress; if there is anything you feel we've
left out, please drop a suggestion to the author or the FAQ Working
Group, and we'll see if we can add it in on the next release. The FAQ
The FAQs owe their existence to the contributors of the net, and as
such it belongs to the readers of rec.aquaria and alt.aquaria.
Articles with attributions are copyrighted by their original authors.
Copies of the FAQs can be made freely, as long as it is distributed at
no charge, and the disclaimers and the copyright notice are included.
Table Of Contents
Before You Buy...
+ Tips to Insure A Successful First Aquarium
+ How Much Time and Effort Is Involved?
* Tank and Equipment
+ Where to Get It
+ What Is Essential
(Tank, Heater, Thermometer, Filter, Gravel, Light and Hood,
Powerhead or Airpump, Stand, Cleaning Tools, Bucket, Nets,
and Test Kits)
* How to Find a Good Aquarium Store
Setting Up Your Tank...
* Preparing Your Water
+ Tap Water
(Chlorine, Chloramine, Other Chemicals)
+ Well Water
* ``Cycling'' Your Tank
+ The Nitrogen Cycle
+ How Much Ammonia Is Too Much
+ Minimizing Cycling-Related Stress
+ Speeding Up the Cycling Process
* Practical Freshwater Chemistry
+ The Big Components:
(pH, Buffering Capacity, General Hardness, Salinity,
Nutrients and Trace Elements)
+ Altering Your Tank Water's Chemistry
(Hardening, Softening, Changing pH)
* Which Test Kits are Important
+ Ammonia (yes)
+ Nitrite (maybe)
+ Nitrate (yes)
+ pH (yes)
+ General Hardness (maybe)
+ Buffering Capacity/KH (maybe)
Setting Up Your Fish...
* Fish Stress
+ The Meaning of Fish Stress
+ Causes of Fish Stress
+ Symptoms of Stressed Fish
* Adding Fish
+ What's a Good Kind of Fish
+ How Many Fish Can one Keep
+ Acclimating New Fish
+ What and How Much to Feed
* Partial Water Changes
+ How Often
* Long-term Success
+ Coping with Algae
+ Coping with Snails
+ Coping with Vacations
+ Coping with Moving
+ Euthanizing Fish
+ Breeding Fish
Beginner FAQ: Introduction
What constitutes success? Healthy fish that live a long time, quite
likely even breeding and having babies. Success also means having a
tank that looks nice without a lot of maintenance (e.g., constantly
battling excessive algae growth).
How To Insure Your First Aquarium Is a Success
Having a successful tank is not difficult, nor is it necessarily a lot
of work, provided you use some common sense. These guidelines are
based partly on science and partly on experience gleaned from
aquarists having many years experience in ``the art of fishkeeping.''
The following list summarizes the most important rules for success.
Each is discussed in more detail in subsequent sections of this
Buying a tank, setting it up and filling it with fish all in the same
day, while possible, is a sure road to disaster. In fact, setting up
and fully stocking your first tank will take close to two months!
An ounce of prevention is worth a pound of cure.
Providing an environment that minimizes fish stress is the key to
success. As fish become stressed, their immune systems weaken and they
become more susceptible to disease. Moreover, most fish medicines
don't work very well, aren't worth the money, and frequently do more
damage than good. Often, the best treatment for sick fish is to
relieve stress by
1. performing regular partial water changes,
2. not overfeeding,
3. checking that your filtration system works,
4. giving them enough room to live, and
5. keeping them with compatible tank mates.
(See the STRESS SECTION of this FAQ for full details.)
Understand and respect the nitrogen cycle.
Fish produce toxic wastes (ammonia) that must be broken down by
bacteria through biological filtration. Most fish deaths for
first-time tank owners are a direct result of not understanding the
nitrogen cycle and are completely avoidable. (The NITROGEN CYCLE
SECTION explains how the process works.)
Perform regular maintenance on your filter to keep it clean.
Dirty (clogged) filters operate at reduced efficiency. In the case of
biological filtration, a clogged filter will be unable to remove
ammonia properly, resulting in fish stress and eventually death.
Floss-based biological filters are cleaned by gently rinsing them in
used tank water that has been siphoned into a bucket. Undergravel
filters are cleaned through regular vacuuming. (Filters are discussed
briefly in this beginner FAQ, and in more detail in their own
Properly treat all tap water before adding it to your tank.
Municipal water contains such added chemicals as chlorine or
chloramine to make it safe for human consumption. These substances are
toxic to fish and can weaken, damage or even kill fish. (See the WATER
TREATMENT section of this FAQ for details.)
Take the time to learn basic water chemistry
Basic water chemistry is pH, hardness and buffering. You needn't
enroll in a chemistry course, but you should know enough about water
chemistry and the specifics of your local water supply so that you can
keep fish happy. Every location's water source is different, and some
fish won't be able to survive in your water. You can learn details
about your water from a local fish store, through the use of test
kits, and from local aquarium clubs (or, amazingly, from the CHEMISTRY
section of this FAQ).
Keep the pH of your tank's water stable.
Rapid pH changes stress fish. Tank water has a natural tendency to
become acidic due to the production of nitric acid (nitrates) from the
nitrogen cycle. Keeping pH stable requires having adequate
``buffering''. If your water is soft, you may need to add buffering
agents. Again, see the CHEMISTRY section for details.
Avoid adding chemicals that lower the pH (e.g. ``pH-Down'').
Such chemicals frequently have undesirable side-effects (e.g.,
stimulate algae growth). Moreover, in most cases (despite what books
and stores tell you) the pH of water DOES NOT need to be adjusted to
make it ``more perfect'' for a particular species of fish. If the pH
of your tap water is between 6.5 and 7.5, it is just fine for most
fish. (This is discussed in the CHEMISTRY section too!)
Pick fish for your water.
Select fish who are native to waters having a similar chemical
properties (pH and GH) to your local tap water. If you have hard
water, choose hard water fish. If you have soft water, choose soft
water fish. This is especially important if you water is outside the
6.5-7.5 pH range. Changing the natural hardness (or pH) of your tap
water can be hard work and often takes the fun out of keeping
aquariums. Moreover, bungled attempts at adjustment are common and
often worse for fish than the original sub-optimal water conditions. A
good way to learn which fish live happily in your local water is to
check with a local fish store (or club).
Choose the fish to fit your tank.
Select fish that are compatible with each other and think long-term.
That 1 inch fish sure looks cute at a store. But what will you do when
it gets 6 inches long and views its cohabitants as potential meals?
Fish have specific minimal space requirements that are dependent on
their physical size and temperament. Select fish whose needs will be
met in your tank. Be sure your tank has adequate hiding places (e.g.,
rocks, plants, driftwood, etc.) for its inhabitants.
Properly acclimate fish before adding them them to your tank.
(Details are covered in the section on ADDING FISH.) NEVER add store
water to your tank (it may contain diseases), and if feasible,
quarantine new purchases for 2-3 weeks before adding them to your
Perform regular partial water changes.
Changing 25% of your tank's water every other week serves two
purposes: it dilutes and removes nitrate before it accumulates to
dangerous levels, and it replaces trace elements and buffers that get
used up by bacteria, plants, etc. Finally, regular partial water
changes help insure that your tank's water chemistry doesn't deviate
significantly from that of your tap water. The latter benefit is
especially important should disease strike your tank; water changes
are the most important step in controlling disease, and large water
changes are not safe unless the chemical composition (e.g., pH and GH)
of your tank's water is similar to your tap water.
Shop only at ``reputable'' stores.
Sadly, many pet stores are more interested in taking your money than
selling you healthy fish. It is almost always worth spending a little
more money to get quality fish. Diseases introduced to your tank with
newly purchase fish may infect your other fish with catastrophic
results. Buying a low cost fish is also not much of a bargain if it
dies less than a month later. But many stores will instead try to sell
you equipment and medications you don't really need. Your best defense
is to arm yourself with knowledge so that you can properly evaluate
their advice. Some hints for finding ``reputable'' stores can be found
in the STORES SECTION.
The above summary serves as a reminder of the principles that lead to
happy fish keeping. Each of these topics (and many more) is discussed
in the remainder of this document.
How much time and effort is involved in keeping a fish tank?
For a 10-20g tank, once it is set up, expect to spend about 30 minutes
every other week doing partial water changes, cleaning the tank, etc.
If this is too much time for you, DON'T GET INTO THIS HOBBY! You will
also spend a few minutes once or twice a day feeding your fish,
turning the lights on and off, etc. Warning: many people spend much
more time than this simply looking at their tank and its inhabitants.
Of course, that is the whole point. :-)
Be prepared to spend several hours researching the hobby before you
make your first purchase. The more time you spend BEFORE you actually
get the tank, the smoother things will go. Go to several pet stores to
find one that looks like a reputable place. Visit them again several
more times. Get some beginner books. Read this beginner FAQ several
Most people who get frustrated with fish tanks made mistakes that
could have been easily avoided. The way to avoid mistakes is to learn
the basics (e.g., the nitrogen cycle) BEFORE you put fish in your
tank. There are few things more upsetting than frantically reading the
FAQ for the first time, while three feet away your beloved fish are
dying. Remember: most aquarium problems are easy to prevent, but hard
to deal with after the fact.
Beginner FAQ: Equipment
Where To Get Your Equipment
All fish stores sell tank setups containing ``everything you need''
for one price. However, a smart shopper looks carefully at what the
package contains to be sure it includes only what you need (and
doesn't include things you don't). Packages vary from store to store,
some are more appropriate than others. Be especially wary of setups
bought at discount stores (e.g., ``Hartz'' brand). They often include
obsolete technology, noisy pumps, cheap heaters, etc.
Garage sales are a great way to get into the hobby cheaply. However, a
few cautions are in order. Before buying the tank, examine it closely
for cracks or scratches. Although cracks can be fixed, doing so is
more hassle (for a beginner) than it is worth. Don't buy a scratched
tank; algae will grow in the scratches making the tank look bad. Be
wary of really old equipment. It may no longer work well.
Before setting up the tank (especially if the tank is used), check it
for leaks. Fill it with water outside and leave it for a week. A leak
on your carport is a lot less of a problem than one in your living
To clean the tank, NEVER use soaps or detergents. Use water and
nothing else. If you want to sterilize the tank, gravel, etc. wash
everything plastic in a mild bleach solution (use pure bleach, not one
with other additives). Rinse everything well in clean water, and let
everything soak a bit in a solution with a bit of added dechlorinator.
(Non-plastic) gravel can be sterilized through boiling.
Equipment: What's Essential and What's Not
Tons of aquarium gadgets are available at pet stores. Some are
essential, others are useful only for specialized applications, and
some are completely useless (though stores selling them probably won't
tell you that). The following checklist shows the items that will
likely to be of use to you.
Tanks come in many shapes and sizes, but there are only two types:
glass and acrylic. You will probably want to get a glass tank. In
cheapest per gallon more expensive per gallon
hard to scratch scratches easily (e.g. scraping algae
with razor blade)
scratches permanent scratches can be buffed out (though
higher index of refraction lower IOR (tank distorts less when
viewed from angle)
empty tank heavy same sized tank weighs less (empty)
(important with tanks >30g)
Tank stand only needs to Special stand needed that supports
support edges entire base of tank (not just edges)
more easily broken harder to break
The size and shape of the tank is completely up to you. However, keep
the following in mind:
1. Contrary to first impressions, larger tanks are not necessarily
more work than smaller ones (within reason, see the TABLES AND
CONVERSIONS for information on large tanks). In particular, it is
easier to keep water chemistry stable in larger tanks than in
smaller ones (the less water, the more easily a small chemical
change causes a big change in relative concentration).
Much of the regular maintenance work does not require twice the
time for twice the size. For example, a regular partial water
change for a larger tank may require one more bucket of water than
for a small tank. That doesn't translate into twice the work,
since you already have the bucket and siphon ready, your hands are
already wet, etc.
2. It is very common for people to really like their fish tank and
want to add more fish. A larger tank can hold more fish safely.
Indeed, a single 10g tank adequately supports only a handful of
medium sized fish.
3. Note, however, that the number of fish that a tank can safely hold
depends not only on the volume of the tank, but on its shape. For
example, some fish spend their entire lives near the bottom.
Doubling the volume of a tank by doubling its height won't allow
you to keep more bottom dwelling fish. Surface area is more
important than volume in determining how many fish a tank can
If possible, start with at 20g (or larger) rather than a 10g (or
smaller). A 20g (``high'' or ``tall'') makes an excellent first tank
size. Avoid all tanks smaller than 10g. They are simply too small to
keep healthy. For example, although many stores sell them, the tiny 1
gallon goldfish bowls are totally inadequate for even a single fish.
Stay away from them!
If you are keeping tropical fish, you will need a heater. A heater
insures that a tank doesn't get too cool, and that the temperature
stays steady during the course of the day, even when the room cools
off (e.g., at night). For many tropical fish, a temperature of 78F is
There are two main heater types. Submersible heaters stay completely
below the water. A second, more traditional style, has a partially
submerged glass tube (which contains the heating coils), but leaves
the controls above the water. Submersible heaters are the better
design, as they can be placed horizontally along the tank's bottom.
This helps keep tank temperature uniform (heat rises), and prevents
the heater from becoming exposed while doing partial water changes.
With the traditional design, one must remember to unplug the heater
before doing water changes; if the heater is accidentally left on
while the coil is above the water, the tube gets hot and may crack
when you fill the tank back up with water.
If your room is never more than 8-10F degrees cooler than your target
tank temperature, a heater of roughly 2.5 Watts per gallon will
suffice. If the differential is higher, up to 5 Watts (or more) per
gallon may be necessary. Remember, the heater needs to keep the tank
at its target temperature, even when the room is at its coldest point;
the tank's temperature should not fluctuate.
Heaters (especially cheap ones) will fail. Most often the contact that
actually turns the heater on and off gets permanently stuck, either in
the on or off position. In the former case, your tank can get VERY
hot, especially if the heater is larger than your tank actually
requires. To minimize potential problems, avoid heaters larger than
the optimal size for your tank. To prevent winter disasters, use two
smaller heaters in parallel rather than one large one. That way if one
fails, the consequences won't be as disastrous.
You will need a thermometer to verify that your tank stays at its
proper temperature. Two types are commonly available. The traditional
bulb thermometer works the same way as the ones you can buy for your
house. They either hang from the top edge of your tank, or float along
the surface. The second common design is a flat model that sticks to
the outside of the glass. In this design, liquid crystals activate at
a specific temperature, either highlighting the numerical temperature
or a bar that slides along a scale.
Aquarium thermometers can be rather unreliable (check out the ones on
display at a fish store --- they should all register the same
temperature, but frequently don't). Thus, thermometers are good for
verifying that your temperature is not too far off, but may be off by
several degrees in some cases. When buying a thermometer, look at all
the thermometers and pick one that has an ``average'' temperature,
rather than one of the extremes.
There are three types of filtration: biological, mechanical and
chemical. Biological filtration decomposes the toxic ammonia that fish
produce as waste products. All fish tanks MUST have biological
filtration; biological filtration is the cheapest, most efficient and
most stable way to breakdown toxic ammonia. Mechanical filtration
traps such particles as plant leaves, uneaten food, etc. (collectively
known as mulm), allowing them to be removed from the tank before they
decompose into ammonia. Chemical filtration (e.g., activated carbon,
zeolite, etc.) can remove (under limited circumstances) such
substances as ammonia, heavy metals, dissolved organics, etc. through
chemistry (e.g., ``adsorbtion'' or ``ion-exchange resins''). Chemical
filtration is mostly useful for dealing with short-term problems, such
as removing medications after they've served their purpose, or
purifying tap water before it goes into a tank. A healthy tank DOES
NOT require the use of chemical filters such as activated carbon.
One point about filtration cannot be made enough. ALL FISH TANKS MUST
HAVE BIOLOGICAL FILTRATION. Although chemical filtration can remove
ammonia under limited circumstances, it are NOT a general solution.
Typical filters perform some or all of the three filtration types in
series. Mechanical filtration (if present) usually comes first (where
it is called a ``pre-filter''), trapping particles that might clog
remaining stages. Biological usually comes next, followed by the
chemical filtration section (if present). Whether or not chemical
filtration is useful (or even helpful) depends on who you talk to. It
can be useful for removing fish medicines after their effectiveness
has ended (partial water changes do the same thing though). They can
also remove trace elements necessary for plant growth (with obvious
results). Unless you have a good reason to believe that your
circumstances require chemical filtration, avoid it.
Filters are not maintenance-free. For example, if debris is allowed to
accumulate in a mechanical filter, it decomposes into ammonia,
negating its primary purpose. Likewise, a biological filter's
effectiveness diminishes as it becomes clogged. Biological filtration
requires water movement across a large surface area on which bacteria
have attached (e.g., floss or gravel). The less surface area
available, the less effective the filter. UGFs are cleaned by
regularly vacuuming the gravel (e.g. while doing partial water
changes). Canister and power filters are cleaned by removing the media
and gently squeezing it in a bucket of used tank water (tap water may
contain bacteria-killing chlorine).
There is no magic formula for what size filter one needs. Consult with
specific manufacturer's ratings and be conservative. You can't have
too much filtering (though you can have too much water movement), so
err on the side of overfiltering. Filters are discussed in more detail
in a separate FILTER FAQ.
Gravel serves three main purposes. First, it serves as decoration,
making your tank look nicer. Second, if using an UGF, gravel is
mandatory as it is the filter media (the surface area on which
bacteria attach). Third, in plant tanks, it serves as a ``substrate''
(e.g. dirt) for plant roots (consult the PLANT FAQ for details on what
quantity and type of substrate is appropriate for plants). Ultimately,
the choice of color, size, etc. is up to you. However, be aware that
dark gravel better highlights a fish's colors. Fish adjust their
colors to match that of the surroundings, and light gravel tends to
wash out a fish's true colors.
Most of the gravel sold for aquariums is plastic coated. For obvious
reasons, you should not boil it. :-) It is also very expensive ($1 a
pound). Gravel can be purchased for much less at patio stores (e.g.,
Wallmart, Home Quarters, local sand and gravel suppliers, etc.).
However, it often tends to be larger than ideal and too light in color
(e.g., marble chips). Sand can also be used.
Be aware that not all gravel is inert. For example, coral, sea shells,
dolomite and limestone will release (leach) carbonates into the tank
raising its pH buffering capacity (see the CHEMISTRY SECTION for
details). When keeping African rift lake cichlids, this is desirable.
But in most other cases, you will not want your gravel affecting the
water chemistry. As a quick test, drip an acid (e.g., vinegar) onto
the gravel in question. If it foams or bubbles, the gravel is going to
leach carbonates into the water. To be absolutely sure, fill a bucket
of gravel with water and measure the pH over a period of a week. If
the pH remains stable, it should be safe to use in your tank.
When used for the first time, gravel should be washed thoroughly.
Simply rinse clean water through it until the water comes out clear
(tap water is fine). For example, put the gravel in a bucket of water,
fill it with water, and churn the gravel up. Drain the water and
repeat the procedure until the water remains clear. Before using
gravel of unknown origin (e.g., not purchased at a fish store), you
may (as a precaution) want to boil it for 15 minutes to kill unwanted
Driftwood and other Decorations
It is safe to place items in your tank as long as they are inert,
meaning they won't release (leach) chemicals into the water. Most
plastics are inert inert, as are glass and ceramic.
Wood may leach substances into the water, changing the pH in a
possibly inappropriate manner. Driftwood often leaches tannins and
other humic acids into the water (much like peat moss), possibly
softening it and lowering its pH. The water may also obtain a
yellowish tea-colored tint. The tint is not harmful and can be removed
by filtering the water through activated charcoal.
If you use wood that you've found yourself (e.g., woods or lake), boil
it first to kill any pathogens. Boiling it (long enough) will also
make it sink.
Lights & Hood
You will probably want to purchase lights and a hood. A hood prevents
fish from jumping out of the tank and reduces the rate at which water
evaporates. A good hood effectively seals the tank (except perhaps
where the heater and filter reside). You want as little water as
possible evaporating as it may raise the room's humidity to
unacceptable levels and requires more maintenance (i.e., you will have
to ``top off'' the tank once or twice a week to replace the lost
There are two styles of hoods. Full hoods combine the light and hood
as a single unit. Hoods include space for only 1 or 2 (parallel)
fluorescent light tubes, which is fine for fish-only tanks, but not
usually enough for growing plants. Glass ``canopies'' cover the tank
with two strips of glass connected by a plastic hinge, but don't
include lighting. A separate strip (or other) light is used in
conjunction with it. Canopies are a bit better for plant tanks than
full hoods; one can upgrade or change the lighting without replacing
the entire hood, and in situations where very high wattage is needed,
one can usually fit more light bulbs directly above the tank.
Light serves two purposes. It highlights and shows off your fish's
colors and provides (critical) energy for plants (if present).
Unfortunately, the two purposes conflict somewhat. In a fish-only
tank, a single low-wattage fluorescent bulb suffices and does a good
job of showing a fish's true colors (most fish don't like bright
lights either). If you want to grow plants, however, more light is
needed, and the bulb's spectrum becomes an issue; be sure to consult
the lighting sections in the PLANT FAQ before purchasing your light
and hood setup.
Whether or not you will be growing plants, fluorescent lights are the
way to go. Incandescent bulbs give off too much heat, causing your
tank to overheat in the summer. Fluorescent bulbs run cooler and use
less electricity for the same amount of light. Note that in the summer
time, even fluorescent lighting can produce enough heat to lead to
tank overheating problems, if your house gets warm (e.g, you live in
the tropics and don't have air conditioning).
Unfortunately, light grows not only plants, but algae. If your tank
contains lots of the kind of light plants desire, and there are no
plants, algae quickly fills the void. Thus, the ideal lighting for
fish-only tanks differs significantly from that for a plant tank. Two
components of light are of particular importance: intensity (i.e.,
wattage) and spectrum. Plants require intense light and certain
spectral ranges produce more growth than others.
Different types of bulbs give off light in different spectral regions.
So-called ``full-spectrum'' bulbs attempt to reproduce the sun's full
spectral range. They are good both for growing plants and bringing out
a fish's natural colors. Specialized ``plant'' bulbs (e.g., gro-lux,
etc.) emphasize a spectral range that stimulates plant growth. Such
bulbs grow plants (and algae!) well, but fish don't look quite right
under them, because the light does not have the spectrum of normal
sunlight. The common ``cool white'' bulbs give off light designed for
humans in windowless offices; they neither grow plants particularly
well, nor bring out a fish's natural colors. As a quick rule of thumb,
2-4 watts/gallon of full-spectrum (or specialized ``plant'') lighting
is good for plants; for fish-only tanks, use less than 1 watt/gallon,
and avoid using plant bulbs.
A powerhead is a water pump that runs completely submerged in a tank.
They typically attach to the ``lift tubes'' associated with UGF
filters, pulling water through the lift tube. The stream of outgoing
water can usually be oriented in (almost) any direction, and it is
common to point them in such a way that water circulates throughout
the tank and stirs up or ``agitates'' the surface a bit.
An air pump simply bubbles air through your tank. Air pumps serve two
purposes. First, they insure that your tank maintains an adequate
concentration of oxygen. An air pump is NOT required for this purpose,
as long as your tank maintains adequate water movement together with
surface agitation. This is generally the case if external (e.g., box
or cannister) filters are used. Second, air pumps can be used to force
water through a filter (e.g., sponge or corner filter). If using a
UGF, for example, an air pump produces bubbles that force water up the
uplift tubes, pulling water through the filter. In larger tanks,
powerheads perform the same function. Thus, an air pump is not
required, provided your tank has good water circulation.
You will need some sort of stand on which to place your tank. The
stand can either be specially designed to hold your tank, or existing
furniture. The first thing to consider is whether your chosen stand
can support the tank's weight. When full of water, tanks weigh a LOT
(the water alone weighs roughly 10 lbs/gallon). Consult THE TABLES in
the INTRODUCTARY FAQ for detailed specs on common aquarium sizes.
If you live in an older or cheaply constructed home, give
consideration to how weight is distributed among the stand's supports.
The larger the surface area of the leg stands, the less instantaneous
pressure (per square inch) on the floor. You don't want the stand to
crash through your floor! If you plan to have a large tank (e.g., 55g
or more), be sure the floor itself can properly support the weight.
For big tanks, try to place the tank perpendicular to the floor joists
(so that the weight is distributed over multiple joists). Placing your
tank near a load bearing wall is also safer than placing in the middle
of your floor.
Stands should keep the tank level, in order to keep weight distributed
properly. An un-level tank places stress in the wrong places,
increasing the odds of having the tank break (yes, this does actually
happen sometimes). In order to more evenly distribute weight on the
stand, it is a good idea to place a 1/4 inch sheet of Styrofoam
between the stand and the tank.
There are two kinds of plants (depending on who you talk to): real and
plastic. Both kinds provide decoration and hiding places for fish.
Plastic plants are (obviously) easier to maintain. Although it is
possible to grow real plants in an aquarium, it is not always trivial
to do so (e.g., plants have special lighting requirements). If you are
at all interested in trying to grow real plants, consult the PLANT FAQ
before purchasing your tank --- especially the hood.
Miscellaneous Cleaning Tools
Siphoning is the easiest way to remove water from a tank. For large
tanks, using a ``water python'' or other long hose allows one to
dispense with the bucket and siphon water directly into a drain or
outside garden. When removing water via siphoning, you should also
clean (``vacuum'') your gravel. Many ``water changing'' hoses are
available at local fish stores and include a gravel cleaning
attachment. The basic idea behind them is to connect a wide mouthed
tube to the end of the siphon hose. When the tube is plunged into the
gravel, the water flow churns up the gravel, but only the detritus
(dirt, mulm, etc) is light enough to be siphoned out. Note that the
dirty water being removed from your tank contains nitrates, which make
an excellent fertilizer for your flower or vegetable garden.
To remove algae from the side of your tank, a plastic, non-soapy
scouring pad can be used. If you have an acrylic tank, be especially
careful that the pad isn't hard enough to scratch the side. Many types
of algae can be wiped free using the floss inserts made for Whisper
filters (cheap and can't scratch).
Some of the slower growing algae simply can't be removed with a
scouring pad without a lot of work (and churning of the tank!). A
razor blade works best at this point. Go to your local fish store and
purchase a scraper that has a long (foot long) handle with a razor
blade on one end. A razor blade can be used to remove just about
anything from the sides of a tank. However, razor blades CAN scratch
glass, if one is not careful.
So-called ``magnet cleaners'' can also be helpful for removing algae.
A scraping block on the inside of the tank is held in place by a
magnet held on the outside of the tank. Moving the outside magnet
moves the scraping block, removing algae without having to plunge your
entire arm in the tank. The best magnet cleaners are those with a
strong magnetic field (e.g., larger magnets), and they work best on
smaller tanks, which have thinner glass.
A toothbrush is one of the most effective tools for removing algae
from the inside of plastic tubing.
Bucket For Water Changes
You will need at least one bucket for adding and removing water from
your tank. Use the largest bucket you can comfortably work with (e.g.,
up to 5 gallons). Use it only for your aquarium and don't ever put any
chemicals in it.
You will need at least one fish net, and having two is better;
catching fish is easier if you use one net to chase fish into the
other. Nets with a fine mesh are harder to use because of their high
water resistance. The right net size will of course depend on the size
of your fish.
Note: netting fish is stressful. In particular, the fish net scrapes
off some of a fish's protective slime coating. If possible, when
catching fish, use a net to chase the fish into a small plastic or
You will probably want to buy some test kits for measuring things like
ammonia concentrations. Because there are so many kits,
recommendations as to which to buy are given in a separate TEST KIT
SECTION of this FAQ.
Beginner FAQ: Finding Reputable Fish Stores
Like all businesses, fish stores have to make money to survive.
Unfortunately, some are more interested in profits than selling you
just what you need and nothing more. Consequently, a smart customer is
a careful shopper.
Of course no store is 100% perfect all the time, but the difference
between a good store and poor one can be astonishing once you've been
to a few. Visit a store several times, and don't rely on just one
experience. If the same bad patterns are present on multiple visits,
find another store.
The following highlights some of the things that distinguish a good,
reputable store from one you should avoid.
If the fish don't look good at the store, chances are they won't
survive long after you bring them home; they may already have been
stressed beyond the point of recovery.
1. A store's fish tanks should be clean and the fish should look
healthy and unstressed (e.g., no nipped fins, good colors, fish
active, etc.). Are dead fish removed quickly? All stores will have
fish die in their tanks; good stores will remove them quickly
(fish covered with fungus have probably been dead a long time).
2. Do any of the fish show signs of disease such as ick (tiny white
spots)? A good store won't sell you ANY fish from a tank that has
ick, even if the specific fish you are purchasing looks OK.
3. Are incompatible fish kept in the same tank? If so, how can you
trust the advice they give you concerning compatible inhabitants
for your tank?
4. Check out the store's policy on fish returns. A good store will
give you full credit on fish deaths for a period of a few days,
provided you bring in a water sample so that they can test your
water for ammonia.
5. Are the sales staff knowledgeable about what they are selling? A
good store will ask you about your tank (size, inhabitants, etc.)
in order to find out whether a prospective fish purchase would be
a good addition to your tank. A bad store will sell you whatever
you want; they'll be happy to sell you more fish later, after
incompatible inhabitants have killed each other.
For beginning aquarists, a good store will take the time to
explain the nitrogen cycle, and advise you to wait on fish
purchases until your tank has become established. A bad store will
neglect to mention the nitrogen cycle, until you return a few days
later wondering wondering why your fish died (now they can sell
you more fish, and maybe ``nitrification bacteria'' to go with
Ask lots of questions. Be wary of vague answers; they are a sign
that the seller doesn't know the answer (and isn't willing to find
out), or worse.
Like that tiny oscar fish? A good store will warn you that oscar
fish get VERY big, and verify that your tank is big enough and
that none of its inhabitants will get eaten by the oscar. A bad
store will remain silent.
6. Be wary of adding medications to your tank; they frequently don't
work or are unnecessary. (See the DISEASE FAQ.) A good store will
first ask about your tank's water quality, verify that cycling has
completed, etc., and suggest water changes. They will also
recommend medications only if they can identify the specific
disease. A ``bad'' store will encourage you to buy medicine,
without regard to whether the specific medicine is useful in
combating the specific problem you have. A good store will ask you
what fish you have in the tank, as some medications are toxic to
certain species of fish. A bad store will let you find out the
7. As a (very) general rule of thumb, stores that specialize in
aquariums are better than stores that sell fish as a sideline. In
the former case, a ``bad'' store won't make money over the long
haul (they can only sucker customers once or twice) and will
eventually go out of business. In the latter case, a store's fish
department may continually lose money, but remain open because the
rest of the store (e.g, puppy sales) is making money. Of course,
there are exceptions.
8. Finally, buying fish at the cheapest store isn't necessarily a
good bargain. A healthy fish is worth paying extra for. A sick
fish may infect all of your tank's inhabitants or die shortly
after purchase; some bargain.
Is a pattern becoming clear? A good store is knowledgeable about the
products they sell and will take the time to be sure the customer is
making a purchase that they will be happy with in the long term. They
want your repeat business in the future. A bad store will encourage
(or fail to discourage) you from buying things you don't need.
Beginner FAQ: Water Treatment
Municipal Tap Water in the Aquarium
Most people use tap water in their tanks; it is cheap and easy to use.
Unfortunately (for aquarists), local water companies add chemicals to
the water to make it safe to drink (e.g., chlorine or chloramine to
kill bacteria). More recently, concern about water flowing through
older lead pipes has caused some water utilities to add pH-raising
chemicals to the water (because lead dissolves less readily in
alkaline water). Consequently, tap water must be specially treated
before it can safely be used in fish tanks.
Another potential problem concerns variability in the chemical
properties of your water supply over time (e.g., month-to-month). Some
water districts don't have enough water themselves, forcing them to
purchase additional water from neighboring water districts in times of
shortages. If this water has a different chemical properties (e.g.,
hardness), your tap water's chemistry will vary as well. As a common
example, high bacteria levels are more of a problem in summer than
winter, especially in warmer climates. Consequently, it is not
uncommon for water companies to use more chlorine in summer months to
keep bacteria in check. Even such factors as local weather can have an
impact; heavy rains may cause the hardness of your water supply to
decrease as local reservoirs fill.
In general, chlorine and chloramine are the two additives that cause
the most problems. Note that these two substances are VERY DIFFERENT!
Be sure you know what is in your tap water and treat appropriately.
In the US, EPA guidelines require that tap water at any faucet contain
a minimal chlorine concentration of 0.2 ppm, and stringently limits
the concentration of bacteria (which may require more than 0.2 ppm
chlorine to keep in check). Because chlorine breaks down over time,
the chlorine concentration of the water that comes out of your tap
will be lower than that put in at water plant. Thus, the exact
concentration at your faucet depends on how far you are from the water
plant, how long it takes the water to travel from the water plant to
your house, how much chlorine is initially added, etc.
Chlorine at high concentrations is toxic to fish; at lower
concentrations, it stresses fish by damaging their gills.
Concentrations of as little as 0.2-0.3 ppm kill most fish fairly
rapidly. To prevent stress, concentrations as low as 0.003 ppm may be
required. Fortunately, chlorine can easily be removed from water by
the chemical sodium thiosulfate, readily available at fish stores
under various brands. Sodium thiosulfate neutralizes chlorine
instantly. Note that there are many ``water treatment'' products that
are advertised as ``making tap water safe''. Read labels carefully.
Inevitably, the ones that neutralize chlorine all contain sodium
thiosulfate, plus other substances that may or may not be useful. If
your water only contains chlorine (as opposed to chloramine), sodium
thiosulfate is all you need. The most cost-effective treatments use
only 1 drop per gallon of water. Most other water treatments are much
more expensive in the long-term; they may require a teaspoon of
treatment (or more) per gallon!
Chlorine is relatively unstable in water, escaping to the atmosphere
on its own. Water left in a bucket (or tank) with adequate water
circulation (e.g. filter or airstone) will be free of chlorine in 24
hours or less.
Many netters report that they perform partial water changes without
ever treating their tap water to remove chlorine. Keep in mind that
even though fish show no APPARENT ill effects from untreated water,
that doesn't mean that the chlorine isn't stressing your fish. How
much stress depends on how much chlorine is introduced to the tank,
which depends on many factors (including the percentage of new water
added). Because chlorine removers are so cheap (pennies per usage),
the insurance they provide should not be passed up.
One problem with using chlorine to treat water is that it breaks down
relatively quickly. Another concern with the use of chlorine is that
it can combine with certain organics (that may or may not be present
in your water) forming trihalomethanes, a family of carcinogens.
Consequently, many water companies have switched from using chlorine
to using chloramine. Chloramine, a compound containing both chlorine
and ammonia, is much more stable than chlorine.
Chloramine poses two significant headaches for aquarists. First,
chlorine-neutralizing chemicals such as sodium thiosulfate only
neutralize the chlorine portion of the chloramine, neglecting an even
bigger problem: deadly ammonia. The consequences can be devastating to
fish. Although a tank's biological filter will (eventually) convert
the ammonia to nitrate, the time it takes to do so may be longer than
what your fish can tolerate.
The second problem relates to water changes. One of the primary
reasons for doing regular water changes is to remove nitrates that
build up. If your replacement tap water contains ammonia, you'll be
putting nitrogen right back into your tank and it will be impossible
to reduce the nitrates below the concentration in your tap water.
Fortunately, tap water concentrations are relatively low (1 or 2 ppm);
you are more likely to have a much higher concentration of nitrate in
Chloramine can be safely neutralized through such products as Amquel,
which neutralize both the ammonia and chlorine portions of the
chloramine molecules. The neutralized ammonia will still be converted
to nitrates via a biological filter.
Another method for neutralizing chloramine is to age the water while
simultaneously performing biological filtration. For example, get an
appropriately-sized (plastic) garbage can, fill it with tap water,
dechlorinate it with sodium thiosulfate, and then connect an
established biological filter to it. Just as in your tank, the bio
filter will convert the ammonia to nitrate, after which it can safely
be added to your tank. Note: you must add sodium thiosulfate to
neutralize the chlorine; otherwise, the chloramine will kill the
bacteria in your biological filter.
Alternatively, the ammonia can removed by filtering the water through
zeolite or carbon before adding it to your tank. [Note: folks report
mixed success with this. If you have concrete (positive or negative)
experience to report, please notify the FAQ maintainers.]
Other water impurities you should be aware of
In addition to the additives described above (chlorine and
chloramine), municipal water may (or may not!) contain other elements
that the aquarist may need to know about. Water in some locations
actually contains nitrates. In some places, water contains elevated
concentrations of phosphates (1 ppm or more). High phosphate has been
linked to algae problems, and a comprehensive algae control strategy
may require removing phosphates. High levels of iron (1 ppm or more)
have also been linked to thread algae. Consult the algae section of
this FAQ for more details.
How to Find out What Your Local Water Company Adds to Your Tapwater
The quick answer is to ask someone who knows. A local fish store (if
they reside in the same water district as you do) should be able to
tell you. Alternatively, call your local water utility. Ask to speak
with the ``water chemist''. Tell them you are an aquarist and want to
know about the pH, GH, and KH of your water, as well as how much the
water characteristics vary from month to month. Finally, (in the US)
if you really want details, have them send you a copy of the periodic
water report they are required to generate for the EPA. It contains a
detailed listing of exactly what your water contains and in what
concentrations (e.g., iron, nitrates, phosphates, etc.). By law, the
report is available for public inspection.
You may have access to well water instead of municipal tap water. One
advantage with well water is that you don't need to deal with chlorine
and chloramine. On the other hand, well water is frequently (much!)
harder than water available through local utilities. In addition, the
only way to know its composition (GH, KH, etc.) is to run tests on it
yourself. Alternatively, there are companies to which you can send
water samples that will perform a detailed analysis of its contents
One potential problem with using well water is that it frequently
contains high concentrations of dissolved gases (which may be
dangerous to fish). For example, well water is frequently
supersaturated with CO2, which lowers the water's pH. Once the CO2
escapes, the pH will increase. Fish shouldn't be subjected to this
temporary pH fluctuation. For safety, aerate well water thoroughly for
several hours before adding it to your tank.
Beginner FAQ: The Nitrogen Cycle, and ``New Tank Syndrome''
What Is the Nitrogen Cycle?
Like all living creatures, fish give off waste products (pee and poo).
These nitrogenous waste products break down into ammonia (NH3), which
is highly toxic to most fishes. In nature, the volume of water per
fish is extremely high, and waste products become diluted to low
concentrations. In aquariums, however, it can take as little as a few
hours for ammonia concentrations to reach toxic levels.
How much ammonia is too much? The quick answer is: if a test kit is
able to measure it, you've got too much (i.e., it's in a high enough
concentrations to stress fish). Consider emergency action (water
changes and zeolite clay) to reduce the danger. (A more detailed
discussion of ammonia toxicity can be found later in this section.)
In aquaria-speak, the ``nitrogen cycle'' (more precisely, the
nitrification cycle) is the biological process that converts ammonia
into other, relatively harmless nitrogen compounds. Fortunately,
several species of bacteria do this conversion for us. Some species
convert ammonia (NH3) to nitrite (N02-), while others convert nitrite
to nitrate (NO3-). Thus, cycling the tank refers to the process of
establishing bacterial colonies in the filter bed that convert ammonia
-> nitrite -> nitrate.
The desired species of nitrifying bacteria are present everywhere
(e.g., in the air). Therefore, once you have an ammonia source in your
tank, it's only a matter of time before the desired bacteria establish
a colony in your filter bed. The most common way to do this is to
place one or two (emphasis on one or two) hardy and inexpensive fish
in your aquarium. The fish waste contains the ammonia on which the
bacteria live. Don't overfeed them! More food means more ammonia! Some
suggested species include: common goldfish (for cold water tanks),
zebra danios and barbs for warmer tanks, and damselfishes in marine
systems. Note: Do not use ``toughies'' or other feeder fishes.
Although cheap, they are extremely unhealthy and using them may
introduce unwanted diseases to your tank.
During the cycling process, ammonia levels will go up and then
suddenly plummet as the nitrite-forming bacteria take hold. Because
nitrate-forming bacteria don't even begin to appear until nitrite is
present in significant quantities, nitrite levels skyrocket (as the
built-up ammonia is converted), continuing to rise as the
continually-produced ammonia is converted to nitrite. Once the
nitrate-forming bacteria take hold, nitrite levels fall, nitrate
levels rise, and the tank is fully cycled.
Your tank is fully cycled once nitrates are being produced (and
ammonia and nitrite levels are zero). To determine when the cycle has
completed, buy appropriate test kits (see the TEST KIT section) and
measure the levels yourself, or bring water samples to your fish store
and let them perform the test for you (perhaps for a small fee). The
cycling process normally takes anywhere from 2-6 weeks. At
temperatures below 70F, it takes even longer to cycle a tank. In
comparison to other types of bacteria, nitrifying bacteria grow
slowly. Under optimal conditions, it takes fully 15 hours for a colony
to double in size!
It is sometimes possible to speed up the cycling time. Some common
procedures for this are detailed later in this section.
Warning: AVOID THE TEMPTATION TO GET MORE FISH UNTIL AFTER YOUR TANK
HAS FULLY CYCLED! More fish means more ammonia production, increasing
the stress on all fish and the likelihood of fish deaths. Once ammonia
levels reach highly stressful or toxic levels, your tank has succumbed
to ``New Tank Syndrome''; the tank has not yet fully cycled, and the
accumulating ammonia has concentrations lethal to your fish.
How Much Ammonia Is Too Much?
In an established tank, ammonia should be undetectable using standard
test kits available at stores. The presence of detectable levels
indicates that your bio filter is not working adequately, either
because your tank has not yet cycled, or the filter is not functioning
adequately (e.g., too small for fish load, clogged, etc.) It is
imperative that you address the problem (filter) in addition to the
symptoms (high ammonia levels).
The exact concentration at which ammonia becomes toxic to fish varies
among species; some are more tolerant than others. In addition, other
factors like water temperature and chemistry play a significant role.
For example, ammonia (NH3) continually changes to ammonium (NH4+) and
vice versa, with the relative concentrations of each depending on the
water's temperature and pH. Ammonia is extremely toxic; ammonium is
relatively harmless. At higher temperatures and pH, more of the
nitrogen is in the toxic ammonia form than at lower pH.
Standard test kits measure total ammonia (ammonia plus ammonium)
without distinguishing between the two forms. The following chart
gives the maximum long-term level of ammonia-N in mg/L (ppm) that can
be considered safe at a given temperature and pH. Again, note that a
tank with an established biological filter will have no detectable
ammonia; this chart is provided only for emergency purposes. If your
levels approach or exceed the levels shown, take emergency action
pH 20C (68F) 25C (77F)
6.5 15.4 11.1
7.0 5.0 3.6
7.5 1.6 1.2
8.0 0.5 0.4
8.5 0.2 0.1
Minimizing Fish Stress During Initial Cycling
Should ammonia levels become high during the cycling process,
corrective measures will need to be taken to prevent fish deaths. Most
likely, you will simply perform a sequence of partial water changes,
thereby diluting ammonia to safer concentrations.
As a final caution, several commercial products (e.g., ``Amquel'' or
``Ammo-Lock'') safely neutralize ammonia's toxicity. Amquel does not
remove the ammonia, it simply neutralizes its toxicity. Biological
filtration is still needed to convert the (neutralized) ammonia to
nitrite and nitrate. Thus, adding Amquel causes the ammonia produced
by the fish to be neutralized instantly, yet still allows the nitrogen
cycle to proceed. Using Amquel during the cycling phase has one
significant drawback, however. Amquel (and similar products) may cause
ammonia test kits to give false readings, making it difficult to
determine exactly when cycling has completed. See the TEST KIT SECTION
It is also possible to cycle a tank without ever adding fish. The role
fish provide in the cycling process is simply their steady production
of ammonia; the same effect can be achieved by adding chemical forms
of ammonia manually (e.g., ammonium chloride). However, it is a bit
more complicated than using fish because the water chemistry needs to
be monitored more closely in order to add the proper amount of ammonia
on a day-to-day basis.
Speeding Up Cycling Time
(For the Impatient)
The nitrogen cycle can be sped up or ``jump started'' in a number of
ways. Unfortunately, they require access to an established tank, which
a beginning aquarist may not have available. The basic idea is to find
an established tank, take some of the bacteria out of it and place
them in the new tank.
Most filters have some sort of foam block or floss insert on which
nitrifying bacteria attach. Borrowing all or part of such an insert
and placing it in the new tank's filter gets things going more
If the established tank uses an undergravel filter, nitrifying
bacteria will be attached to the gravel. Take some of the gravel (a
cup or more) and hang it in a mesh bag in your filter (if you can), or
lay it over the top of the gravel in the new tank (if it has an UGF).
If you have a box, sponge or corner filter, simply connect it to an
established aquarium and let it run for a week or so. Bacteria in the
water will establish a bed in the new filter. After a week, move the
now ``seasoned'' filter to the new tank.
More recently, products containing colonies of nitrifying bacteria
have become available at pet shops (e.g., ``Fritz'', ``Bio-zyme'',
``Cycle''). In theory, adding the bacteria jump-starts the
colonization process as above. Net experience with such products has
been mixed; some folks report success, while others report they don't
work at all. In principle, such products should work well. However,
nitrifying bacteria cannot live indefinitely without oxygen and food.
Thus, the effectiveness of a product depends on its freshness and can
be adversely effected by poor handling (e.g., overheating).
Unfortunately, these products don't come with a freshness date, so
there is no way to know how old they are.
Some (not many) aquarium stores will provide aquarium buyers with a
cup of gravel from an established tank. A word of caution is
appropriate here. Due to the nature of the business, tanks in stores
are very likely to contain unwanted pathogens (bacteria, parasites,
etc.); you don't want to add them to an established tank. For someone
setting up their very first tank, however, all fish will probably be
purchased from the same store, so the danger is relatively small, as
the newly purchased fish will have been exposed to the same pathogens.
If possible, seed a filter with bacteria from a non-store tank.
Of course, there are many variations on the above that work. However,
it is a bit difficult to give an exact recipe that is guaranteed to
work. It is advisable to take a conservative approach and not add fish
too quickly. In addition, testing the water to be sure nitrates are
being produced eliminates the guesswork of determining when your tank
Beginner FAQ: Practical Water Chemistry
What You Need to Know About Water Chemistry, and Why
Water in nature is rarely pure in the ``distilled water'' sense; it
contains dissolved salts, buffers, nutrients, etc., with exact
concentrations dependent on local conditions. Fish (and plants) have
evolved over millions of years to the specific water conditions in
their native habitats and may be unable to survive in significantly
Beginners (especially the lazy) should take the easy approach of
selecting fish whose needs match the qualities of their normal tap
water. Alternatively, an advanced (and energetic!) aquarist can change
the water characteristics to match the fish's needs, though doing so
is almost always more difficult than first appears. In either case,
you need to know enough about water chemistry to ensure that the water
in your tank has the right properties for the fish you are keeping.
Water has four measurable properties that are commonly used to
characterize its chemistry. They are pH, buffering capacity, general
hardness and salinity. In addition, there are several nutrients and
pH refers to water being either an acid, base, or neither (neutral). A
pH of 7 is said to be neutral, a pH below 7 is ``acidic'' and a pH
above 7 is ``basic'' or ``alkaline''. Like the Richter scale used to
measure earthquakes, the pH scale is logarithmic. A pH of 5.5 is 10
times more acidic than water at a pH of 6.5. Thus, changing the pH by
a small amount (suddenly) is more of a chemical change (and more
stressful to fish!) than might first appear.
To a fishkeeper, two aspects of pH are important. First, rapid changes
in pH are stressful to fish and should be avoided. Changing the pH by
more than .3 units per day is known to stress fish. Thus, you want the
pH of your tank to remain constant and stable over the long haul.
Second, fish have adapted to thrive in a (sometimes narrow) pH range.
You want to be sure that your tank's pH matches the specific
requirements of the fish you are keeping.
Most fish can adjust to a pH somewhat outside of their optimal range.
If your water's pH is naturally within the range of 6.5 to 7.5, you
will be able to keep most species of fish without any problems. If
your pH lies within this range, there is probably no need to adjust it
upward or downward.
Buffering Capacity (KH, Alkalinity)
Buffering capacity refers to water's ability to keep the pH stable as
acids or bases are added. pH and buffering capacity are intertwined
with one another; although one might think that adding equal volumes
of an acid and neutral water would result in a pH halfway in between,
this rarely happens in practice. If the water has sufficient buffering
capacity, the buffering capacity can absorb and neutralize the added
acid without significantly changing the pH. Conceptually, a buffer
acts somewhat like a large sponge. As more acid is added, the
``sponge'' absorbs the acid without changing the pH much. The
``sponge's'' capacity is limited however; once the buffering capacity
is used up, the pH changes more rapidly as acids are added.
Buffering has both positive and negative consequences. On the plus
side, the nitrogen cycle produces nitric acid (nitrate). Without
buffering, your tank's pH would drop over time (a bad thing). With
sufficient buffering, the pH stays stable (a good thing). On the
negative side, hard tap water often almost always has a large
buffering capacity. If the pH of the water is too high for your fish,
the buffering capacity makes it difficult to lower the pH to a more
appropriate value. Naive attempts to change the pH of water usually
fail because buffering effects are ignored.
In freshwater aquariums, most of water's buffering capacity is due to
carbonates and bicarbonates. Thus, the terms ``carbonate hardness''
(KH), ``alkalinity'' and ``buffering capacity'' are used
interchangeably. Although technically not the same things, they are
equivalent in practice in the context of fishkeeping. Note: the term
``alkalinity'' should not be confused with the term ``alkaline''.
Alkalinity refers to buffering, while alkaline refers to a solution
that is a base (i.e., pH > 7).
How much buffering does your tank need? Most aquarium buffering
capacity test kits actually measure KH. The larger the KH, the more
resistant to pH changes your water will be. A tank's KH should be high
enough to prevent large pH swings in your tank over time. If your KH
is below roughly 4.5 dH, you should pay special attention to your
tank's pH (e.g, test weekly, until you get a feel for how stable the
pH is). This is ESPECIALLY important if you neglect to do frequent
partial water changes. In particular, the nitrogen cycle creates a
tendency for an established tank's pH to decrease over time. The exact
amount of pH change depends on the quantity and rate of nitrates
produced, as well as the KH. If your pH drops more than roughly two
tenths of a point over a month, you should consider increasing the KH
or performing partial water changes more frequently. KH doesn't affect
fish directly, so there is no need to match fish species to a
Note: it is not a good idea to use distilled water in your tank. By
definition, distilled water has essentially no KH. That means that
adding even a little bit of acid will change the pH significantly
(stressing fish). Because of its instability, distilled (or any
essentially pure water) is never used directly. Tap water or other
salts must first be added to it in order to increase its GH and KH.
General Hardness (GH)
General hardness (GH) refers to the dissolved concentration of
magnesium and calcium ions. When fish are said to prefer ``soft'' or
``hard'' water, it is GH (not KH) that is being referred to.
Note: GH, KH and pH form the Bermuda's Triangle of water chemistry.
Although the three properties are distinct, they all interact with
each other to varying degrees, making it difficult to adjust one
without impacting the other. That is one reason why beginning
aquarists are advised NOT to tamper with these parameters unless
absolutely necessary. As an example, ``hard'' water frequently often
comes from limestone aquifers. Limestone contains calcium carbonate,
which when dissolved in water increases both the GH (from calcium) and
KH (from carbonate) components. Increasing the KH component also
usually increases pH as well. Conceptually, the KH acts as a
``sponge'' absorbing the acid present in the water, raising the
Water hardness follows the following guidelines. The unit dH means
``degree hardness'', while ppm means ``parts per million'', which is
roughly equivalent to mg/L in water. 1 unit dH equals 17.8 ppm CaCO3.
Most test kits give the hardness in units of CaCO3; this means the
hardness is equivalent to that much CaCO3 in water but does not mean
it actually came from CaCO3.
0 - 4 dH, 0 - 70 ppm : very soft
4 - 8 dH, 70 - 140 ppm : soft
8 - 12 dH, 140 - 210 ppm : medium hard
12 - 18 dH, 210 - 320 ppm : fairly hard
18 - 30 dH, 320 - 530 ppm : hard
higher : liquid rock (Lake Malawi and Los Angeles, CA)
Salinity refers to the total amount of dissolved substances. Salinity
measurements count both GH and KH components as well as such other
substances as sodium. Knowing water's salinity becomes important in
salt water aquariums. In freshwater tanks, knowing pH, GH and KH
Salinity is usually expressed in terms of its specific gravity, the
ratio of a solution's weight to weight of an equal volume of distilled
water. Because water expands when heated (changing its density), a
common reference temperature of 59F degrees is used. Salinity is
measured with a hydrometer, which is calibrated for use at a specific
temperature (e.g., 75F degrees is common).
One component of salinity that neither GH or KH includes is sodium.
Some freshwater fish tolerate (or even prefer) a small amount of salt
(it stimulates slime coat growth). Moreover, parasites (e.g., ick) do
not tolerate salt at all. Thus, salt in concentrations of (up to) 1
tablespoon per 5 gallons can actually help prevent and cure ick and
other parasitic infections.
On the other hand, some species of fish do not tolerate ANY salt well.
Scaleless fish (in general) and some Corydoras catfish are far more
sensitive to salt than most freshwater fish. Add salt only if you are
certain that all of your tank's inhabitants prefer it or can at least
Nutrients and Trace Elements
In addition to GH, KH, pH and salinity, there are a few other
substances you may want to know about. Most tap water contains an
assortment of nutrients and trace elements in very low concentrations.
The presence (or absence) of trace elements can be important in some
* nitrates, which are discussed in great length in this FAQ in
conjunction with the NITROGEN CYCLE;
* phosphates, the second most prominent nutrient. Phosphates have
been linked to algae growth. If you have persistent algae
problems, high phosphates may be a contributing factor. In a plant
tank, ideal phosphate levels are .2 mg/L or lower. To control
algae, frequent partial water changes are often recommended to
reduce nutrient levels. If your tap water contains excess
phosphate, water changes may be aggravating the situation. Your
local water company can tell you what the exact phosphate levels
* iron, manganese and other trace elements. Plants need iron in
trace quantities to grow. Tap water in many areas contains no iron
at all. Consult the PLANT FAQ for more details.
Altering Your Water's Chemistry
Hardening Your Water (Raising GH and/or KH)
The following measurements are approximate; use a test kit to verify
you've achieved the intended results. Note that if your water is
extremely soft to begin with (1 degree KH or less), you may get a
drastic change in pH as the buffer is added.
To raise both GH and KH simultaneously, add calcium carbonate (CaCO3).
1/2 teaspoon per 100 liters of water will increase both the KH and GH
by about 1-2 dH. Alternatively, add some sea shells, coral, limestone,
marble chips, etc. to your filter.
To raise the KH without raising the GH, add sodium bicarbonate
(NaHCO3), commonly known as baking soda. 1/2 teaspoon per 100 Liters
raises the KH by about 1 dH. Sodium bicarbonate drives the pH towards
an equilibrium value of 8.2.
Raising and Lowering pH
One can raise or lower pH by adding chemicals. Because of buffering,
however, the process is difficult to get right. Increasing or
decreasing the pH (in a stable way) actually involves changing the KH.
The most common approach is to add a buffer (in the previous section)
whose equilibrium holds the pH at the desired value.
Muriatic (hydrochloric) acid can be used to reduce pH. Note that the
exact quantity needed depends on the water's buffering capacity. In
effect, you add enough acid to use up all the buffering capacity. Once
this has been done, decreasing the pH is easy. However, it should be
noted that the resultant lower-pH water has much less KH buffering
than it did before, making it more susceptible to pH swings when (for
instance) nitrate levels rise. Warning: It goes without saying that
acids are VERY dangerous! Do not use this approach unless you know
what you are doing, and you should treat the water BEFORE adding it to
Products such as ``pH-Down'' are often based on a phosphoric acid
buffer. Phosphoric acid tends to keep the pH at roughly 6.5, depending
on how much you use. Unfortunately, use of phosphoric acid has the BIG
side effect of raising the phosphate level in your tank, stimulating
algae growth. It is difficult to control algae growth in a tank with
elevated phosphate levels. The only advantage over hydrochloric acid
is that pH will be somewhat better buffered at its lower value.
One safe way to lower pH WITHOUT adjusting KH is to bubble CO2 (carbon
dioxide) through the tank. The CO2 dissolves in water, and some of it
forms carbonic acid. The formation of acid lowers the pH. Of course,
in order for this approach to be practical, a steady source of CO2
bubbles (e.g. a CO2 tank) is needed to hold the pH in place. As soon
as the CO2 is gone, the pH bounces back to its previous value. The
high cost of a CO2 injection system precludes its use as a pH lowering
technique in most aquariums (though see the PLANT FAQ for inexpensive
do-it-yourself alternatives). CO2 injection systems are highly popular
in heavily-planted tanks, because the additional CO2 stimulates plant
Softening Your Water (i.e., lowering GH)
Some fish (e.g., discus, cardinal tetras, etc.) prefer soft water.
Although they can survive in harder water, they are unlikely to breed
in it. Thus, you may feel compelled to soften your water despite the
hassle involved in doing so.
Typical home water softeners soften water using a technique known as
``ion exchange''. That is, they remove calcium and magnesium ions by
replacing them with sodium ions. Although this does technically make
water softer, most fish won't notice the difference. That is, fish
that prefer soft water don't like sodium either, and for them such
water softeners don't help at all. Thus, home water softeners are not
an appropriate way to soften water for aquarium use.
Fish stores also market ``water softening pillows''. They use the same
ion-exchange principle. One ``recharges'' the pillow by soaking it in
a salt water solution, then places it in the tank where the sodium
ions are released into the water and replaced by calcium and magnesium
ions. After a few hours or days, the pillow (along with the calcium
and magnesium) are removed, and the pillow recharged. The pillows sold
in stores are too small to work well in practice, and shouldn't be
used for the same reason cited above.
Peat moss softens water and reduces its hardness (GH). The most
effective way to soften water via peat is to aerate water for 1-2
weeks in a bucket containing peat moss. For example, get a (plastic)
bucket of the appropriate size. Then, get a large quantity of peat (a
gallon or more), boil it (so that it sinks), stuff it in a pillow
case, and place it in the water bucket. Use an air pump to aerate it.
In 1-2 weeks, the water will be softer and more acidic. Use this aged
water when making partial water changes on your tank.
Peat can be bought at pet shops, but it is expensive. It is much more
cost-effective to buy it in bulk at a local gardening shop. Read
labels carefully! You don't want to use peat containing fertilizers or
Although some folks place peat in the filters of their tanks, the
technique has a number of drawbacks. First, peat clogs easily, so
adding peat isn't always effective. Second, peat can be messy and may
cloud the water in your tank. Third, the exact quantity of peat needed
to effectively soften your water is difficult to estimate. Using the
wrong amount results in the wrong water chemistry. Finally, when doing
water changes, your tank's chemistry changes when new water is added
(it has the wrong properties). Over the next few days, the chemistry
changes as the peat takes effect. Using aged water helps ensure that
the chemistry of your tank doesn't fluctuate while doing water
Hard water can also be softened by diluting it with distilled water or
R/O water. R/O (reverse-osmosis) water is purified water made by a R/O
unit. Unfortunately, R/O units are too expensive ($100-$500) for most
hobbyists. R/O water can also be purchased at some fish stores, but
for most folks the expense and hassle are not worth it. The same
applies to distilled water purchased at grocery stores.
Beginner FAQ: Test Kits
Which Are Useful?
There is a seemingly endless array of test kits for testing everything
from ammonia levels to phosphate levels. Does one really need to buy
them? The quick answer is no. It is quite possible to have a healthy
tank without ever buying a single test kit. However, test kits are
extremely useful at eliminating guesswork when something goes wrong
(e.g., fish appear stressed or die). In the following, we describe the
test kits that are most useful and the conditions under which they are
Ammonia Test Kit
Get one. Ammonia test kits are cheap ($5-10) and will tell you whether
your tank has elevated ammonia levels. This is useful in two
circumstances. First, during the tank-cycling phase, regular testing
for ammonia will tell you when the first phase of the nitrogen cycle
has completed. Second, should you have unexplained fish deaths,
testing for ammonia verifies that your biological filter is (or is
not) working correctly. Note that even in an established tank, the
biological filter can sometimes weaken or fail outright. Common causes
* not cleaning the filter regularly (water can't flow through a
clogged filter, where the nitrifying bacteria reside),
* naively adding fish medicines (antibiotics kill nitrifying
bacteria (oops) as well as disease carrying ones),
* having too small a filter for the fish load, etc.
Be warned: if you have fish deaths and subsequently ask the net (or a
fish store) for advice, the first question asked will be ``What are
your ammonia (and nitrite) levels?''.
Ammonia levels are measured in ppm. At concentrations as low as .2-.5
ppm (for some fish), ammonia causes rapid death (consult the CYCLING
SECTION for further details). Even at levels above 0.01-0.02 ppm, fish
will be stressed. Common test kits don't register such low
concentrations. Thus, test kits should NEVER detect ammonia in an
established tank. If your test kit detects ANY ammonia, levels are too
high and are stressing fish. Take corrective action immediately by
changing water and identifying the source of the problem.
Warning: Amquel and other similar ``ammonia-neutralizing'' water
additives are incompatible with most ammonia test kits. Water treated
with Amquel will falsely test positive for ammonia, even when ammonia
is not present. Test kits using the ``Nessler'' method are known to
give false readings under such conditions.
Nitrite Test Kit
You might want to get one of these; nitrite kits are cheap ($5-10) and
are useful in the same circumstances where an ammonia test is useful.
The only time a nitrite kit provides information that an ammonia kit
can't is while testing for completion of the second phase of the
nitrogen cycle (see the CYCLING SECTION). As in the case for ammonia,
if your test kits detects nitrite, your biological filter is not
working adequately. Once a tank has cycled, nitrite kits are pretty
much useless. (If the bio filter in an established tank isn't working,
both ammonia and nitrite levels will be elevated.)
Nitrite is an order of magnitude less toxic than ammonia. Thus, one
common saying about tank cycling is: ``if your fish survive the
ammonia spike, they'll probably survive the nitrite spike and the rest
of the cycling process.'' However, even at levels above .5 ppm, fish
become stressed. At 10-20 ppm, concentrations become lethal.
Nitrate Test Kit
Get this kit! Nitrate levels increase over time in established tanks
as the end result of the nitrogen cycle. (The only exception to this
rule is heavily-planted tanks and some reef tanks, which MAY be able
to consume nitrogen faster than it is produced.) Because nitrates
become toxic at high concentrations, they must be removed periodically
(e.g., through regular water changes). Having a nitrate test kit helps
you determine whether or not your water changes are removing nitrates
Nitrates become toxic to fish (and plants) at levels of 50-300 ppm,
depending on the fish species. For fry, however, much lower
concentrations become toxic.
Note: A nitrate test kit is only of limited value in determining
whether the nitrogen cycle has completed. Most nitrate test kits
actually convert nitrate to nitrite first, then test for the
concentration of nitrite. That is, they actually measure the combined
concentration of nitrite and nitrate. In an established tank, nitrite
levels are essentially zero, and the kits do properly measure nitrate
levels. While a tank is cycling, however, a nitrate kit can't tell you
how much of the reading (if any) comes from nitrate rather than
pH Test Kit
Get one; these kits are extremely cheap, so there is no excuse for not
owning one. You will want to know the pH of your tap water so that you
can select fish whose requirements meet your water conditions. In
addition, you will periodically want to check your tank's pH so that
you can be sure it stays stable and doesn't increase or decrease
significantly over time.
In some cases, tank decorations (e.g., driftwood) or gravel (e.g.,
made of coral, shells or limestone) change the pH of your water. For
example, tank items may slowly leach ions into your tank's water,
raising the GH and KH (and pH). With driftwood, it is not uncommon to
have the wood slowly leach tannins that lower the pH.
General Hardness (GH) Kit
You may want to get one of these, but having one is not critical. You
don't need to know the exact hardness level. Knowing whether your
water is ``soft'', ``very soft'', etc. is good enough. Your local fish
store may be able to give you sufficient information. Alternatively,
call your water utility (see the TAPWATER SECTION of this FAQ).
Carbonate Hardness (KH) Kit
This kit is not critical to have. By regularly monitoring the pH, you
can figure out whether your KH is ``high enough''. That is, the KH
should be high enough that your pH stays stable over time. If you have
trouble keeping the pH stable, you may want to increase your tank's
buffering capacity. Your local fish store may be able to give you
sufficient information as to your KH value. Alternatively, call your
A KH kit is, however, indispensable to plant enthusiasts who use CO2
injection. It is also strongly recommended that you get one if you
want to change the pH of your water, and it is a very useful
diagnostic tool if you are experiencing pH stability problems.
Fish Stress and Healthy Fishkeeping
What Stress Means, and Why it is Bad for Your Fish.
Most fish can tolerate environmental conditions that differ somewhat
from the natural conditions in which they evolved. This does not mean,
however, that they will be as healthy or live their full normal life
span. For example, keeping a fish in water that is cooler (or warmer)
than its preferred condition forces its body organs to work harder to
keep it alive. That is, such conditions place the fish under increased
Increased stress reduces a fish's ability to ward off diseases and
heal itself (e.g., if its fins get nicked, or parasites get introduced
into the tank with newly purchased fish). In addition, stress reduces
a fish's ability to breed successfully and shortens its natural life
span. A small amount of stress by itself is not usually fatal, but as
stress levels increase, a fish's ability to cope with it decreases.
Thus, one of the most important goals of a fishkeeper is to remove
sources of stress wherever possible.
It should be noted that eliminating stress does not guarantee that
your tank will be healthy. But it significantly increases the odds.
Many netters boast regularly about how they've kept fish (apparently)
``healthy and happy'' for long periods of time under (apparently)
highly stressful conditions. Such aquarists are sitting on a
time-bomb; the not uncommon followup story will refer to one fish
getting sick, then another, with an end result of multiple fish
deaths. Reducing stress simply increases the likelihood that a tank
will stay healthy (much the same way as eating right, exercising and
getting the proper amount sleep is generally associated with a long
healthy life for humans).
Common Causes of Stress in the Aquarium
In this section, we list some of the more common stress-inducing
conditions. In all cases, the level of stress induced by a specific
factor is highly species-dependent. You should be aware of the type of
stress that will be present in your tanks and select fish known to
tolerate such conditions well. For example, if your water is hard and
alkaline, you're best off selecting fish that thrive under such
Nitrogen compounds (ammonia, nitrite and nitrate) have varying degrees
of toxicity and are stressful at all levels. Ammonia is toxic in low
concentrations and severely stresses fish under ANY concentration.
Consequently, a healthy aquarium must have an adequate biological
filter that quickly converts ammonia to nitrite (and nitrate).
Although significantly less toxic than ammonia or nitrite, nitrate
also stresses fish. Thus, a means of removing excess nitrate (e.g.,
through regular water changes) helps keep an aquarium healthy.
The water temperature of your tank should match the needs of its
inhabitants. Keeping water temperature too cold or too warm for a
particular species will stress those fish. For example, goldfish
prefer cooler temperatures (under 70F) than most tropical fish
(goldfish survive winters in ponds where temperatures approach
freezing), guaranteeing that a tank containing both goldfish and
tropicals will either be too cold or too warm for some of the
Some fish prefer soft water, others prefer hard water. Keeping a
soft-water preferring fish in harder water (and vice versa) is
Some fish prefer acidic water, some prefer alkaline water, others
prefer water with a neutral pH. (Some fish don't care too much.)
Some fish live in brackish water conditions; they will do better in
water with a small amount of added salt. Other species are extremely
intolerant of salt. Add salt only if all of a tank's inhabitants can
tolerate salinity. Mollies, for example are known to like salt,
whereas many species of catfish tolerate no salt at all. In general,
fish lacking scales (or having small scales) don't tolerate salt well.
The amount of physical space required for a particular fish depends on
its species. Some fish do just fine in a 10g tank, others need 100g or
more. Keeping a fish in a tank that is too small for it increases the
level of stress (on everyone), frequently leading to increased
aggression among tank inhabitants. Note also that the amount of space
required may change should fish pair off to breed. Cichlids, for
example, claim a portion of the tank for themselves when in breeding
form, chasing away any fish that encroach on their territory. Thus,
the onset of breeding behaviors frequently increases stress levels.
Not all species of fish mix well with others. As an obvious example,
most cichlids will eat smaller tank inhabitants (e.g., anything they
can fit in their mouths). Even if too big to be eaten, however,
peaceful fish will be stressed if kept with aggressive fish that chase
them around all day. Moreover, many fish communicate through behavior
and body language (i.e., cichlids frequently establish a ``pecking
order'' in which one fish is king). Fish of one type of species may
not recognize the signals given off by others, guaranteeing continual
Some fish school in nature, spending their entire lives in large
groups (rather than individually); they never feel comfortable or
``safe'' when kept by themselves. Cory cats for example, do better in
a tank with 6 or more other Corys than they do by themselves. While it
may be tempting to buy six different kinds of fish, this may not be
ideal for the fish themselves. The opposite can also be true. Some
fish are more aggressive towards members of their own species (e.g.,
mating behaviors), whereas they may not feel threatened by other
species and pretty much ignore them.
Fish need oxygen, and some fish are more tolerant of low-oxygen water
than others. Water with insufficient oxygen stresses fish. Note that
as the water temperature goes up, the amount of dissolved oxygen in
Poor nutrition also causes stress. A healthy diet is a varied diet,
and one should avoid using old foods in which vitamins and other
nutrients have broken down. ``Old food'' includes food that has been
stored in hot places, been exposed to air (not sealed), etc.
The ``cure'' of adding medicines to tanks is often worse than the
original disease. Medications that kill bacteria, parasites, etc. are
usually not too discerning: they may also kill your nitrifying
bacteria (now you REALLY have a major problem) or be toxic to the fish
themselves. For example, some species of fish do not tolerate certain
types of medicines at all. Adding such medications may weaken healthy
fish to the point that they become susceptible to the original
Adding untreated water to your tank may introduce chlorine or
chloramine, both of which are toxic to fish. Be sure to treat all
water prior to adding it to your tank.
Sudden changes in water conditions can be stressful. Within limits,
most fish can adjust to sub-optimal water conditions (e.g., wrong
temperature, wrong pH). However, fish have difficulty adjusting to a
SUDDEN change in water chemistry. Thus suddenly raising (or lowering)
the temperature, changing the pH, changing the water hardness, etc.
stresses a fish. It is more important to keep the water chemistry
stable over the long haul than to keep keep water conditions exactly
In summary, many factors lead to fish stress. Minimizing and
eliminating sources of stress increases the chances of keeping tank
inhabitants healthy. The exact amount of stress an individual fish can
take depends greatly on what species it is, its age and size, etc. A
stressed fish is a weakened fish. Although it may appear healthy to
the casual observer, it will be more susceptible to disease, injury,
etc. In contrast, healthy (unstressed) fish will be able to ward off
disease and infection on their own. Thus, the appearance of disease in
a tank is frequently brought on by ``poor water conditions'' that
leave fish with weakened immune systems.
Symptoms That Your Fish Is Stressed
In short, stressed fish don't ``act normal'' (with ``normal'' defined
according to the species of fish). Once you've had fish for a few
weeks, you'll see that each species behaves in its own characteristic
way (that's why fish are fun to have!). Some fish tend to always stay
near the top of the water, others near the bottom. Some fish swim
continuously, others stay in one place. Deviation from their norm
usually indicates stress.
Common symptoms of stress include:
* Fish stays near the surface gasping for breath, indicating that it
has trouble getting enough oxygen (the concentration of dissolved
oxygen is highest near the water's surface). Possible causes
include low oxygen concentration due to poor water circulation,
toxins that have damaged its gills, high ammonia or nitrite
* Fish won't eat, or doesn't eat as aggressively as in past.
* Fish stays hidden continuously and won't come out where it can be
seen. Possible causes: aggressive fish, insufficient cover (e.g.,
plants, wood, etc.) to make fish feel ``safe'' while swimming
* Fish has nicked fins, open wounds that don't seem to heal.
Possible cause: fish is target of aggression. Normally, minor
nicks and cuts heal quickly. If they don't, stress levels may be
suppressing the fish's immune system.
* Fish has disease (parasites, fungus, etc.) Of course, the disease
itself is a major problem. But in most cases, a healthy fish's
immune system keeps it from getting sick in the first place. Thus,
getting sick is a sign that the fish is in a stressed state (or
had been until recently).
Beginner FAQ: Adding & Feeding Fish
Contributed by Lots Of Writers
So you've got your tank set up and the filter running, you know about
the nitrogen cycle and a little water chemistry. You've got all your
test kits poised and ready to monitor your first month. Armed with
this knowledge, you make your way to the local fish store to buy your
first fish (or two). In this section, we'll deal with some of the
common questions about keeping your fish. (Whew! Didn't think we'd
actually get to fish, did you?)
Selecting ``Good'' Fish
There are so many things to say about good beginner fish, we've
covered it in a whole separate FAQ (oddly-enough, called the GOOD
BEGINNER FISH FAQ); it contains many suggestions for particular fish.
Here is the author's general advice:
If we define a good beginner's fish as one that is easy to feed and
care for, hardy, able to live in a variety of water conditions, and
attractive, then there are a number of widely available fish which fit
the bill nicely. Many of these are regularly sold as beginner's fish.
But watch out! Many of the fish sold as beginner's fish really are not
well suited to that role.
Many of the smaller schooling fish make ideal first fish. These
include White Cloud Mountain Minnows, the several commonly available
species of Danios and Rasboras, and most available species of Barbs.
For those with a slightly larger tank, Rainbowfish make a great
schooling fish. Corydoras Catfish are ever popular schooling catfish.
While many beginners are tempted to get just one or two of each of
several different schooling fish, this should be resisted. Schooling
fish do better if there are several of their own species present for
them to interact with. A minimum of six of each of the midwater
schooling fish is recommended, while four is the bare minimum for
Corys. In the long run, a school of a dozen fish showing their natural
behavior will be more pleasing than a mixed group of fishes unhappily
forced to share the same tank. (``Mom, why is that one fish hiding
behind the heater and that other one just hanging in the corner?'')
How Many Fish Can Be Added?
The easiest answer to that question is ``one fish at a time.'' As far
as how many in total can safely survive, a frequently used
rule-of-thumb is ``up to a maximum of 1 inch of fish per gallon.''
Much discussion of this rule has suggested that it really should read
``up to a maximum of 1 inch of SLIM-BODIED fish per gallon.''
``Slim-bodied'' could be fish such as neon tetras, White Cloud
Mountain Minnows, danios etc.; ``medium bodied'' might be red-tailed
black sharks, tiger barbs, platys, cory cats etc.; ``heavy bodied''
would be goldfish, oscars etc.
In other words, this is only a rule of thumb, and the ``maximum''
population that is safe and humane will vary from tank to tank.
Factors that increase your possible fish load include:
* regular and significant water changes,
* HEALTHY live plants, and
* more than one type of well-tended filtration (remember to think of
your filter as alive; it needs care just as do your fish).
Likewise, factors that decrease your possible load include:
* erratic or sparse water changes,
* no plants or UNhealthy live plants, and
* limited or ill-tended filtration (an undergravel filter can do a
great job, but if it fails for some reason and was the only
filtration on the tank, a heavily stocked tank will experience
much more disastrous consequences than one with a light load).
So, back to adding fish. Often it is not practical to add fish one at
a time - for instance, you find some especially great looking neons
and want to add a small school (6 or 7 fish) to your recently cycled
20 gallon tank. You currently have one 2-inch pl*co and three 1.5-inch
platys. Adding the neons will essentially double the ``volume'' of
fish in the tank. In this case, you will see the same effects as
cycling your tank, i.e., an ammonia and nitrite spike before the
bacteria grows to match the new fish population. Test your water
frequently and be prepared to do emergency partial water changes if
the ammonia levels go up too far.
The bio-filter for your tank is only ``fed'' by the wastes of the fish
you have in the tank. This means that no matter how large your filter
(e.g., one rated for a fully stocked 50 gal tank on your 20 gal), the
bacteria population will be limited by the ``food'' it has. Few fish =
small bacteria population.
We are accustomed to thinking of bacteria reproduction as
``explosive''. Many bacteria can double their population size in
hours, after all... but as we have seen in the CYCLING SECTION, the
appropriate nitrifying bacteria are relatively slow to reproduce.
There will be a time delay between the increased waste production of
additional fish, and increased waste processing by the bacteria. In
extreme cases, the ammonia increase could harm or kill your fish
before the bacteria population had time to ``catch up'' to the amount
of available nitrogenous wastes.
This is why it is wise to add fish slowly and gradually. Safely
bringing your tank's population up to the maximum load can take more
than 6 months; in fact, it should be permitted to take at least that
long. Leave breaking the rules to those with more years experience
than they have fish.
Acclimating the Fish to Your Tank
(adapted from the SALTWATER BEGINNER FAQ)
Once you get the fish home you should set the bag in your tank,
allowing the temperature to equalize. After about a half an hour or
so, add a 1/4 cup of tank water to the bag. Repeat this process once
every 15 minutes for an hour, removing any water if the bag gets too
full. Any water you remove from the bag should be disposed of. It will
most likely contain parasites and other bad things.
After you have the fish acclimated to your tank's water chemistry,
there are a couple of things you can do. You can place the fish
directly into the main tank and hope for the best, or you could place
the fish into a quarantine tank. In either case, quickly net the fish
from the bag to the tank so that no store water gets transferred to
The best scenario is to place the fish in quarantine. Keep the fish in
the quarantine tank for 2 weeks and watch for signs of disease. If the
fish gets sick, you can medicate the quarantine tank without affecting
the chemistry of the main tank's. If you are going to quarantine the
fish, you should acclimate the fish to the quarantine tank's
chemistry, not the main tank.
While a quarantine tank is a good idea, it is most likely that you do
not have such a luxury (for now, at least... :). In this case, be
extra careful to select healthy fish at the store, and carefully
monitor your new arrivals for the first few weeks in your tank for
signs of stress and disease. You always risk infecting the other fish
in your tank when skipping quarantine.
Feeding the Fish
Most common fish sold in aquarium shops, especially those recommended
for beginners, can subsist on processed (flake, stick or pellet) food.
Some can even thrive on it... although for fish, just as for other
animals, some variety in the diet is usually desirable.
Fish food is somewhat delicate. Exposing it to sunlight, leaving the
lid off so that damp can come in, or buying a very large container
that takes 8 months to use up all can sabotage the nutritional value
of your fish's food. Generally speaking, there are five classes of
* various processed foods (processed ground stuff remade into
flakes, sticks or pellets; often divided into categories for
omnivorous, vegetarian, and carnivorous fish),
* freeze dried foods (whole beasties such as blood worms, daphnia
* frozen foods (more whole beasties),
* live foods (live beasties), and
* other fresh foods (home made carnivore food of beefheart, zucchini
for your pl*co, etc).
To many fishkeepers, flake food is like rice. It will do for most
every meal, but a little something else now and again is important.
Nearly every new fishkeeper will hear the rule ``feed your fish only
what they will eat in 3 minutes'' or similar blandishment. This is
terrifying to the beginner; after all, those fish are obviously
ravenous! What if they starved! This is only a tiny pinch! How can it
Take it seriously. The reason most folks have fish is, we hope, to
observe them. If not up close and personal, at least in a general
sense. The perfect time to do some of your observing is when you feed.
Each time you feed, park yourself in front of the tank to watch. Put
in less than you think can possibly be enough. Watch the fish consume
it. Observe what falls to the bottom. If you don't have any fish who
are primarily bottom feeders (pl*cos, corydoras, loaches etc.), take
the time to learn if any of your other fish will glean the bottom;
gouramis often will, but rainbows generally won't, for example. If you
do have bottom feeders, watch to see how fast they eat.
So you put a little pinch in, and after 2 minutes (you counted!) there
is practically no food to be seen... except a little on the bottom
which the cories are really going for. Yep, you can probably safely
give them some more. But watch to make sure they really eat all of the
second pinch too. It is better to feed a tiny bit several times a day,
especially with fish who won't scour the bottom, than it is to feed a
bunch all at once... but most adult fish will do fine being fed a 5
minute ration once a day. In an established tank, even less often is
preferred by some fish keepers; that way, the fish will eat more of
the algae and other edibles that can naturally occur in a tank.
Another thing to keep in mind: fish CAN get fat, especially if fed a
lot of rich foods such as bloodworms. Many of the fish you'll buy to
put in your tank are juveniles: how they develop into adult fish will
be determined by your care of them. Just as high nitrates can stunt a
fish's growth, shorten its life, and prevent it from ever breeding
successfuly, fish who are overfed can end up with deformed bodies and
other problems - plus they poop more... which has obvious
ramifications :-). Feeding a good variety of foods ensures that your
fish will get not only the rich foods, but also fiber (brine shrimp
and other crustaceans) and vegetables (algae foods, vegetables).
A word on live foods: certain commercially available live foods are
considered risky by many hobbyists, as they can carry parasites -
tubifex worms in particular. You will have to decide yourself how you
feel about this risk. Be very sure that you are feeding food that is,
indeed, still alive! Rinse the critters thoroughly, and especially if
they are not able to live in your tank water, be just as careful about
overfeeding live food as you are other foods. Live foods are covered
in detail (including culturing instructions) in the LIVE FOOD FAQ.
Beginner FAQ: Partial Water Changes
Purpose of Water Changes
The solution to pollution is dilution; water changes replace a portion
of ``dirty'' water with an equal portion of clean water, effectively
diluting the concentrations of undesirable substances in your tank. In
an established tank, nitrate is the primary toxin that builds up.
Regular water changes are the cheapest, safest and most effective way
of keeping nitrate concentrations at reasonable levels. During the
tank cycling phase, however, ammonia or nitrite may be the substances
that need to be diluted and removed. Likewise, if medications have
been added to your tank, they may need to be removed after they've
served their primary purpose.
The effectiveness of water changes is determined by two factors: their
frequency and the percentage of water that is replaced. The more often
water is replaced, or the greater the quantity of replaced water at a
change determines overall effectiveness.
The benefits of water changes must be balanced by the stress caused by
a sudden change of your tank's water chemistry. If tank water has
similar pH, GH and KH as tap water, changing 50% (or more) of the
water at one time will not affect fish. On the other hand, if your
tank's pH is (for example) 6.3, while your replacement water has a pH
of 7.5, replacing 50% of the water all at once will change the pH of
your tank significantly (possibly more than 50% depending on buffering
factors), which will stress your fish, possibly enough to kill them.
Because water changes are the first line of defense in dealing with
problems such as disease, you want to be able to do large, frequent
partial water changes during emergency periods. Consequently, you want
your tank's water chemistry to closely match that of your replacement
water. That way, you always have the option of performing large water
changes on short notice. Note that this is the way tanks start out;
when you initially set up your tank, the water is the same as that
from your tap. Over time, however, the tank's water chemistry may
``drift'' relative to tap water due to acidification from the nitrogen
cycle, the addition of chemical additives such as ``Ph-up'' or
``Ph-down'', the use of non-inert tank gravel (e.g. crushed coral or
sea shells), etc.
How frequently should partial water changes be made?
The more frequent the changes, the less water that needs to be
replaced. However, the longer between changes, the more stressful each
change potentially becomes, because a larger portion of the water gets
replaced. Replacing roughly 25% of your tank's water bi-weekly is a
good minimal starting point, but may not be enough. The proper
frequency really depends on such factors as the fish load in your
tank. Nonetheless, you should do water changes often enough so that
1. nitrate levels stay at or below 50ppm, and preferably MUCH lower
(less than 10ppm is a good optimal value);
2. the change in water chemistry resulting from a change is small. In
particular, the before and after pH of your tank shouldn't differ
by more than .2 units. (Use a test kit the first few times to get
a feel for what's right.) If your pH changes too much as a result
of a water change, perform changes more frequently, but replace
less water at each change.
Water changes remove nitrates after they've been produced. Nitrogenous
substances in the form of uneaten fish food, detritus, etc. can also
be removed BEFORE they get broken down into nitrate. This is achieved
by cleaning your mechanical and biological filter regularly, and by
vacuuming the gravel with a gravel cleaner. This should be done every
time you perform a water change, e.g., every two weeks.
Note: if your heater becomes partially exposed to air as the water
level drops while doing changes, be sure to unplug your heater while
doing your water changes. The heater can crack if the water level
drops below the heating coil!
Also, be sure to dechlorinate/dechloriminate the replacement water
before adding it to your tank! (See the WATER TREATMENT section.)
Contributed by Lots Of Writers
In this last section, we bring up popular issues that come up after
your tank has been running for a while.
Stopping that !@*!@ Algae Plague
You should first be aware that not all algae is ``bad''; Algae, like
plants, feed off nutrients in the tank, so a good crop of
regularly-harvested algae can help keep the pollution levels in check
(this is the principle behind ALGAL SCRUBBER filtration). Likewise,
algae plagues are usually symptoms of overfeeding or not enough water
changes. The best thing to do is to learn what is causing the plague,
and eliminate that cause. Test your nitrate and/or ammonia. Increase
your water change volume and/or frequency, or feed your fish less.
There are also a number of chemical remedies for specific algae types,
and algae-eating fish which will consume some algaes. For full
details, including specific remedies, please consult the ALGAE SECTION
of the DISEASE FAQ.
Snails, like algae, can be both useful and detrimental to a tank. Some
species will burrow in the gravel, aerating it and keeping it from
being compacted; others will eat algae. However, some species will
reproduce unchecked, destroying plants and generally being an eyesore.
You can protect against snails by sanitizing anything inanimate you
add to your tank in a 1:20 bleach solution, and treating new live
plants in potassium permangenate or Alum. For ridding your tank of
snails, you have little recourse other than vacuuming as many up as
possible, though clown loaches are rumored to eat snails. The SNAIL
SECTION of the DISEASE FAQ describes individual species of snails and
What to do on Vacations
Healthy fish can easily go a week without food. When you go out of
town for the weekend, don't bother getting someone to feed your fish.
(Indeed, someone not familiar with fish tanks is likely to overfeed
your fish while you are gone, leaving you a mess to deal with when you
return.) Stay away from those ``vacation feeders'' that slowly
dissolve. They can upset the pH of your tank and lead to excessive
food in your tank. Electrically-operated automatic feeders, though,
can be useful as you ``pre-measure'' the amount of food it dispenses
If you're going away for longer than a week you will have to make
arrangements for someone to feed the fish. Tank minding companies and
some fish stores will do this for a fee, but most people ask a friend
or neighbor who doesn't keep fish themselves. Sustained overfeeding
could overload your filter and wipe out your tank, and the best way to
avoid the risk of this happening is to make up individual packages
(such as small envelopes) each containing a day's worth of food. The
fish don't have to be fed every day, and shouldn't be given more than
one day's normal amount of food at a time, even if they've gone a few
days without. Be sure to warn your helper not to make up for days they
have missed by giving extra food.
If your tank has a high evaporation rate you may also want to arrange
for it to be topped off with fresh water. This is most important in a
marine tank, as you don't want the salinity drifting too high.
You can't guarantee there won't be a major equipment failure or some
other kind of disaster while you're away, but you can minimize the
risk by replacing any suspect equipment well in advance (so you can be
sure the replacement is working). Don't add any new fish in the month
before your vacation in case they introduce disease that takes some
time to come to light. Clean your tank and filter and do a normal
water change before you go, but if you've neglected maintenance don't
wait until the day before you leave and then blitz it. That will
stress your fish and perhaps damage your filtration bacteria just when
they least need it.
If there is a serious problem, the chances are that it will be
discovered too late to do anything about it. However, looking after
someone else's fish can feel like a heavy burden of responsibility,
and your helper might have better peace of mind if they have the
number of a fish store or some other source of expert advice to call
in an emergency.
Moving a Tank
contributed by Timothy Shimeall
The best word on moving fish (and in this discussion, fish includes
all aquarium animal life), beyond very short distances, is DON'T.
Travel is very stressful on fish, and even with the best precautions
you should expect to lose several. Given that this is true, you may
want to seriously consider selling off your stock and getting new fish
at your destination.
If, given the above, you still want to try to move fish, then the
following may help to minimize the pain and loss of fish.
The task of moving fish splits into two tasks: moving the tank, and
then (later) moving the fish. Never attempt to move the fish in their
Moving the tank
The main problem in moving the tank is the filtration system. After a
very few hours (less than a day) without a flow of oxygen-laden water,
aerobic bacteria start to die. If you are moving a short distance (a
few hours' drive or so), it may be possible to preserve your bacteria
colony; even for longer drives, some of the bacteria will survive and
rebuild itself quickly. With a modest amount of ingenuity and
planning, it should be possible to minimize the down time of the
filter by keeping water flowing though the media until the last
possible minute and restarting it as soon as you arrive. It is
advisable to always try to save your old filter media rather than
throw it away.
The moving procedure is as follows:
1. Put your fish in a holding container (more on that below)
2. Drain your tank. If the move is going to be short, preserve some
of the water to help preserve the bacteria colony.
3. Disassemble your tank. Aquarium plants will survive a fair amount
of time if their roots are kept wet, so it should be possible to
bag them with some water and set them aside for hand-moving. If
the move is going to be short, put your (unrinsed) filter medium
in a sealed container (preferably a never-used pail or other
chemical-free hard-sided container); keep the media wet, but not
submerged. For long moves (more than one day), either clean or
discard your filter media. Pumps, heaters, etc. can be packed as
any fragile appliance.
4. Move your tank. Don't use a moving company or professional
packers, unless you have absolutely no choice AND you can
supervise them packing the tank and loading it in the truck. It's
far better to move it yourself or with the help of friends.
5. Reassemble your tank at your destination. If you're doing a short
move you should have enough dechlorinated/treated water available
on arrival to fill your tank and get water moving through your
filter. If you're doing a long move, then set your tank up as if
it was a new tank-- including a week-long delay before putting
fish in the tank. Initially, put in a few hardy fish to get the
nitrate cycle established. After the tank is stable, put the fish
from your old home back in.
Moving the fish
There are three problems in moving the fish:
1. Where do you put them?
You have two options: a friend's tank, and a pet store tank. Some
pet stores will, for a fee, board fish during a move. A signed
contract, detailing what responsibilities the pet store is
assuming, is a very good idea. Some pet stores, for a further fee,
will pack and air-ship the fish to you on request. This isn't
cheap. Bear in mind that you'll be leaving the fish there for at
least a couple of weeks.
2. How do you pack them?
For short periods of time (a couple of hours, tops) you can put
the fish in sealed bags, half-filled with air. This time can be
stretched somewhat by filling with oxygen, rather than air. Put
the bags in a padded, compartmentalized container, and ship by
air. (This is how pet stores receive their fish). For larger fish,
or longer trips, one can use a sealed bucket for each fish, rather
than a bag.
3. How do you support them on the move?
Fish won't eat during the move. They're too stressed, and you
don't want to degrade the water quality by the food, anyway. Fish
can survive a week or so without food if they've been previously
well fed. Try to maintain an even temperature, perhaps by placing
the fish in a sealed cooler, or compartmentalized cooler. For long
trips, particularly by car, a battery-powered airpump and airstone
is a good idea (if not a must). After the move, slowly condition
the fish to the new tank location, as you would in adding new fish
to a tank.
It's come to this has it? You've read all the FAQs, found out
everything you can about diseases, ailments and the proper treatments,
asked for help from several knowledgeable sources and have come to the
conclusion that you cannot nurse your fish back to health. And since
you took on the responsibility of caring for the fish you now must
find the most humane method in helping it to die.
Several options exist for euthanizing your ill pet. They include
chemicals, decapitation, and donation. The best method is probably
through the use of chemicals. A few vets recommend an overdose of
MS-222, a fish anesthetic. It can be purchased from chemical supply
companies as MS-222, tricaine methanesulfonate or Ethyl
3-aminobenzoate, methanesulfonic acid salt. Immerse the fish in a
container of 350 ppm MS-222 (350 mg MS-222 per liter of water) for 10
minutes. This is very humane and is non-traumatic for both the fish
and owner. Another chemical method is the injection of pentothal into
the abdominal cavity. This may be more difficult for the owner as
syringes may be hard to come by and sticking animals with needles may
not sit well with some people. It is almost painless for the fish if
this helps ease your hesitations regarding this method. Finally one
can use alcohol to euthanize a fish. Make a 1:5 (20%) solution of
Vodka (or any other similar strong grain neutral alcohol) and water.
Then place the fish into the container and it will simply `go to
sleep'. These 3 methods are highly recommended as they are very
One method that has been recommended by a non-veterinary (but
experienced Oscar breeder) type is the use of Alka-Seltzer. Place the
fish in a shallow container of water and place 2 Alka-Seltzer tablets
in a position under the gills. The fish supposedly will `fall asleep'
A non-chemical but effective method is decapitation. Once again, some
owners may be squeamish over this method. If done properly is quick
and painless for the animal, and has the benefit of being cheap; most
of us own knives but not anesthetics. Use a sharp knife and sever the
spinal cord by quickly cutting down through the body just behind the
eye at the level of the lateral line. The quicker you make this cut
the better it will be for the fish. Remember to disinfect this knife
after the procedure if you plan on using it for anything other than
If you are unable to go through with any of the above methods try
contacting a local university. It is possible that one of the
departments in biology or similar fields will take your sick fish off
your hands. They may use the fish for research and study its disease
or will be able to dispose of it properly.
Methods that are not recommended but are often mentioned include
variations on freezing. Fish tend to suffer in these procedures. It
does not matter whether they cool down slowly when you place them in a
bowl of water in the freezer or if the water is already cold from the
addition of ice cubes. Fish react to these methods in a negative way,
and it is painful to watch. Finally one should NEVER flush a fish down
the toilet. This is not an effective method of euthanasia but is a
form of torture as the fish ends up in a septic tank or similar place
where it is bathed in nasty chemicals and sewage before finally
succumbing hours if not days later.
Breeding Your Fish
At some point, you will find yourself unsatisfied with merely keeping
healthy fish, and will yearn to delve into the fascinating world of
fish breeding. Congratulations! You've gone beyond the scope of the
FAQs. Go read some good books on fish breeding, and post questions to
the newsgroups. Then write a FAQ on it,. :) [Editor's note: someone
has taken us up on the challenge! There is a BREEDING FAQ at last.]
End of Beginner FAQ.