Fishes face lots of dangers once they leave the relative shelter of the aquatic store, adding fishes to a new aquarium needs to be done with great care so as not to stress the fishes too much, or even cause them a worse fate. You owe it to the fishes that you buy, to take great care of them, just as you would any other animal that you would foster.



After setting up a new aquarium, and when you are satisfied with your water test results, one or two hardy fishes can be introduced. These will produce enough waste to feed the bacteria and build up their numbers. When adding fishes you should never just tip them straight out of the bag into the aquarium, the temperature in the bag will be different to the temperature of the water in your aquarium.

Fishes should be acclimatised gently otherwise they could be shocked, which would leave them prone to disease. Instead, place the unopened bag in your aquarium for about 15 minutes, to start equalising the temperature, then open the bag and add a small amount of aquarium water to it, leave this for 5 minutes, then repeat until the temperature of the waters are equal, before gently letting the fishes swim out of the bag.

Don't be tempted to add any more fish stock just yet, this is a crucial stage. Using your test kits you should monitor the ammonia and nitrite levels every couple of days while the bacteria multiply, it's not unusual for the nitrite level to increase at this stage, and it should soon fall back. Over the next two weeks do your tests regularly. If you find unacceptable levels of nitrite you should do a partial water change, not too much mind, try about 10% daily until it falls back.

When you are satisfied that levels have remained stable, you can add another small batch of fish. Once again, remember to closely monitor ammonia and nitrite levels for a couple of weeks before adding another small batch of fish. Gradually build up to the recommended stocking levels for the dimensions of your aquarium, over an 8 to 10 week period.

How many Fish?

If you want to know how many fishes your freshwater tropical aquarium can accommodate, simply multiply your aquariums length by width in inches and divide by 12, this is the total amount of fish in inches that your aquarium can support.

If you want the metric version: measure your aquarium in centimetres, divide by 30, this will give you the amount of fish in centimetres. Example.

24 x 12 x 12 inches aquarium, 24 x 12 = 288 divided by 12 = 24 inches of fish.

60 x 30 x 30cm aquarium, 60 x 30 = 1800 divided by 30 = 60 cm of fish.

New Tank Syndrome:

When setting up a new aquarium, and/or filter, you must monitor things closely in the first 4 to 6 weeks (which is what I have been explaining above), especially after adding new fish stock. As mentioned earlier, beneficial bacteria have to build up, and until then, a phenomenon known as New Tank Syndrome can occur, and could cause problems.

During the starting up process there is a characteristic rise and fall in the concentrations of ammonia and nitrite, with levels possibly becoming toxic, and causing fishes to become unhealthy. This is due at this stage to fish waste and uneaten food accumulating in the aquarium and not being broken down by the nitrifying bacteria, i.e. the Nitrogen Cycle.

Do water tests every two or three days.

Do not over feed, once a day is more than adequate, and only the tiniest amount.

Don't think you're being cruel, far from it.

More fishes eating more food means more waste, and your filters won't cope with the sudden surge of fish waste.

Be patient, it takes time to mature an aquarium and its filters, and you will benefit in the long run by having less problems and being successful.

If you do experience a problem with your water quality, replace about 10% - 20% of it, per day, or every other day, so that you bring toxic levels down to normal, remember to treat the new water the way you did initially. Never replace more than 50% of your water at any one time (you will just end up with new water and be back to square one).

It's better to carry out smaller water changes over a few days, rather than change large volumes of water at any one time. When you do a water change try to get as much debris from the aquarium and gravel as possible, this task will be made easier with a gravel cleaner, and without clouding the water too much.

New tank syndrome can have a range of effects on fishes, some of which include, gasping at the surface, rapid gill movement, rubbing against objects. They will also be prone to diseases like fin rot, fungus and whitespot, and may even die. What you must bear in mind is that if it is new tank syndrome, it is likely that all the fishes will be affected, if it is only one or two it would probably be an introduced disease.

If you use common sense and try to understand the needs of the fish, and the processes of nature, you will be well on your way towards setting up a successful aquarium. You can sit back and enjoy your creation. You've followed the steps that will lead to more enjoyment from your hobby, rather than having to worry what on Earth went wrong!