Cycling
There is one more step that needs to be completed before you can add the fish and this
step probably the most crucial of them all. The water in which the fish live is a whole
new ecosystem in itself. There are other microorganisms living in this water beside the
fish, algae and plants. All the living organisms in your aquarium will produce waste that
can become toxic. Fortunately, there is also a class of organisms that work in tandem to
decompose this waste and to make it beneficial for the habitat. Understanding this basic
but sometimes overlooked fact and doing your best to aid this process will make your
aquarium a definite success.
Why probe into the details when you know that the waste that will be produced will also
be efficiently decomposed? Well, since the ecosystem in an aquarium is an artificial one
that you have created it can sometimes require your assistance. An aquarium that is just a
few weeks or days old is at its most fragile. The water is new; microorganisms in the
water may be beneficial or toxic. The key here is to minimize the undesirable organisms
while boosting the colony of desirable and helpful bacteria. This is where the
NITROGEN CYCLE comes in.
Nitrogen based substances are the most frequent byproducts of decomposition. The
Nitrogen cycle refers to the process in which this decomposition takes place. Nitrogenous
waste products in your aquarium will first break down into ammonia. Ammonia can be
very toxic for fish. If ammonia can be detected by your test-kit, then the levels are too
high for your fish.
Nitrifying bacteria are the microscopic organisms that aid the nitrogen cycle and convert
harmful ammonia to a more harmless form - nitrate. In nature, there are vast colonies of
these bacteria, but when you first set up your aquarium this type of bacteria is only
minimal in your water. In the first few weeks, you have to induce this bacterial colony to
multiply and reach an optimum level. A good nitrifying bacterial colony goes a long way
in ensuring the health of your aquarium. The initial period when this bacterium is being
coaxed to multiply is known as cycling the aquarium.
Certain conditions are optimal for the growth of the nitrifying bacteria. They grow well in
areas that have a rich supply of oxygen. Lesser sunlight means less heat and less light.
These are ideal for the growth of bacteria. Portions of the aquarium that are not disturbed
by currents, and are relatively unmoved are also good breeding grounds for the nitrifying
bacteria. This is however only the first half of the nitrogen cycle.
Slowly, as nitrites get converted, nitrates start building up. The second half of the
nitrogen cycle converts the nitrites into nitrates which are relatively harmless through a
process called denitrifying. This is then converted into nitrogen gas, which escapes into
the air. It is however impossible to get rid of all the fish waste by simply letting nitrogen
gas evaporate. If you do not perform frequent water changes, the levels of nitrate will
sooner or later become high enough to seriously harm your fish and eventually kill it.
Your aquarium can never be a perfectly balanced ecosystem. You are for instance adding
new organic compounds to the system every time you feed your fish.The nitrogen cycle begins when the aquarium is provided with a little bit of ammonia.
One great way to do this is to add natural plants. The leaves falling off from these plants
supply the first doses of nitrogen. Other methods include adding a pinch of flake food,
adding a sliver of fish or shrimp to the water. Using some gravel or water from another
aquarium is also a good way to kick starting the cycle since gravel or water from an
established aquarium will be filled with the two necessary types of bacteria. Care must be
taken to ensure that there is no infection in the water. Commercial products containing
nitrifying bacteria are available in many pet shops and can be used to speed up the
process.
Another very popular means of starting off the cycling process is using 'cycling fish'.
Adding no more than one or two hardy and inexpensive fish, e.g. Zebra Danios, to the
aquarium will introduce the necessary nitrites into the water. Do not over-feed the fish,
because this will lead to the production of more ammonia than the yet fragile balance can
handle. Using feeder fish as cycling fish is generally not recommend, because feeder fish
is sometimes unhealthy and may introduce diseases into your aquarium.
Use your test kit to follow the ups and downs of the nitrogen cycle. In the cycle,
remember that the nitrite levels will first go up and then fall to zero. This process may
take 2-6 weeks. The speed in which the cycle completes will depend upon the
temperature in your aquarium. It is however usually ok to start adding fish after 1-2
weeks since the bacteria colonies then has grow to a large enough size to support fish as
long as the fish are sparsely fed. You should never add fish if the ammonia or nitrates
level still are high in the aquarium. The ammonia levels should be non-detectable before
adding fish.