Ethical Considerations While Cycling an Aquarium
Filters have to be matured there is no getting around that, because fish
excrete Ammonia and Ammonia is toxic to fish. It is the bacterial
colonies which grow in the filters and on all the surfaces within the
aquarium that break down Ammonia first into Nitrites and finally into
Nitrates. But until there are enough bacteria within these colonies
there will be an excess of Ammonia and Nitrite in the water and both of
these compounds are HIGHLY toxic to fish.
It has been a long standing practice to use some cheap fish to get this
cycle going and keep them until there was enough bacteria to breakdown
the Ammonia and Nitrite. It appeared and once this stage had been
reached the aquarium was said to be mature and safe for other fish.
Ammonia is extremely toxic to fish even when it is present in the
tiniest imaginable amount, just one part ammonia in ten million parts of
water is enough to cause stress, illness and even the actual death of
some delicate species. Fortunately help is at hand in the form of some
types of bacteria, these bacteria consume the ammonia as it is produced
so there is never any free ammonia in the water once there are
sufficient numbers of these helpful bacteria present.
The whole point of maturing or cycling the tank is to build up the
numbers of these helpful bacteria so that there are sufficient numbers
of them to cope with a tank full of fish. But this isn't the end of the
process because these helpful bacteria which consume the ammonia have a
big downside, they produce nitrite and nitrite is almost as deadly to
fish as ammonia. But there is another species of bacteria which consume
the nitrite and turn it into nitrate which is relatively harmless unless
it reaches very high levels.
Obviously this was a very unsatisfactory way to go about things because
presumably anyone who set up an aquarium did so because they had an
interest in fish and so it seemed ironic that the first thing you had to
do to get started in this hobby was to kill or injure some fish.
The old method
The old method of maturing a fish tank was to place a few cheap fish in
the tank after it had been set up and then let the ammonia build up when
the fish excrete it. Once the ammonia was present the bacteria which
consume it would begin to multiply and produce nitrite which in turn
meant that the bacteria which consume the nitrite would begin to
multiply. Unfortunately the levels of ammonia and nitrite levels would
build up to such high levels that some of the fish would die and others
would suffer from ill health both in the short term and in the long
Why subject something you like and something you have an interest in to
Causes fish to produce extra mucus over its gills, which means that they
will work less effectively and leave the fish gasping to get enough
oxygen, it also damages the small capillaries and they haemorrhage. The
fish will also begin to twitch and swim erratically. Death will soon
Cause damage to the fishes haemoglobin and makes it unable to carry
Oxygen the result of this is the fishes tissue dies and it develops deep
ulcers and secondary infections again death soon follows.
Set the new tank up with
all its equipment, decorate it to your liking and fill it up. Switch
the lights and filters on and leave it running as though there were
fish in it.
After 48 hrs there may be
a little cloudiness present in the water, this is entirely normal - do
nothing. The cloudiness will disappear but it could take from a few
hours to several days.
Once it has gone add some
ammonia to the water - this can be in the form of unscented household
ammonia or something which will produce it such as a piece of meat the
size of a thumbnail. As the meat breaks down it will produce the
required ammonia, but this method is more difficult to control. The
household ammonia is preferable because it is cleaner to use and more
When using the ammonia
solution add just 1 drop for every ten litres of water on alternate
days. If the tank is a tropical tank set the temperature to 85F whilst
the tank is cycling because the bacteria's metabolism will be around
its peak at this temp and the cycling process will be speeded up as a
After about four days test
the water for ammonia and nitrite. The results may or may not show any
nitrite but keep testing two or three times per week until the nitrite
level reaches 15 parts per million.
Once this target has been
reached stop adding the ammonia and just wait.
A few days later the
ammonia levels will have disappeared but the nitrite will probably
hold steady for a time. The time it takes cannot be guessed at because
there are to many variables which affect it. I have personally known
it take from 11 days to 5 weeks and then out of the blue the nitrite
begins to fall. Once it starts to fall it disappears quite rapidly,
usually within hours
When it has disappeared
without any trace return the temp to its normal level of about 76F and
then the first fish can be added to the tank,
Don't add to many or what
you have done so far will be wasted.
Add the first FEW fish
i.e. 4 or 5 small fish.. The newly cycled tank won't be completely
stable for the first few weeks so great care must be taken to keep the
tank clean and not to over feed the fish.
After two weeks or so some
more fish can be added and this is how you should proceed for the
first 6 months of the tanks life.
This is a much faster method if you have access to an already mature
Set up the tank and
equipment and run it as though there were fish already in it.
After 48 hrs take some
filter media from the already established aquarium (about 1/3rd of the
total) and add it to the new filter. Replace this media from the
original mature filer with new media which will be colonised by
bacteria very quickly.
24 hrs later you can start
adding the fish. Again this has to be done very gradually.
Adding water from a mature
tank won't help in the slightest with the maturing process. It is a
If you run a hospital tank
or isolation tank from time to time you can place a small sponge filter
at the rear of an established tank and keep it running there. This will
ensure that it is always mature and ready for use at a moments notice so
that a hospital tank could be set up and in use within minutes