Aquarium Fish Deaths - Some Causes And Remedies

You've set up your aquarium, added some fish and are looking forward to enjoying your new hobby. everything looks fine for a while then slowly the water becomes cloudy, or the fish start to die or algae overtake the tank. What did you do wrong? More importantly what can you do to achieve that sparkling tank with healthy fish that you see in all the pictures?

The first thing not to do is panic and rush to the nearest pet shop, buy a load of chemical treatments and dump them in the tank! This will, in all probability, only make things worse. Another thing people new to the hobby tend to do is completely clean out the tank and start again. This is again the wrong thing to do as any beneficial bacteria that you have succeeded in growing in your tank will be removed and you will have to start all over again. You need to understand some basic facts about your hobby first then apply some sensible methods to cure the problems.

We have put together some frequent causes of fish deaths and other aquarium problems with our recommended cures.

Toxic Chemical Build Up

Fish can die for a number of causes but the most common is a build up of toxic ammonia, nitrites and less often nitrates. Ammonia is a waste product of the fish and if left in the tank will cause harm to the fish. Bacteria in the tank convert the ammonia to nitrites, which are also toxic, but then to the much less toxic nitrates. The bacteria are encouraged to grow when you cycled the new tank. You did cycle the tank correctly? If you added too many fish before the tank was cycled this will inevitably lead to build up of these chemicals and could easily be the reason the fish are dying.

Bullying Fish

Some types of fish are peaceful when young but grow into bullies that can hound other fish to death. Tiger barbs are notorious for being bullies. Did you notice that they are always kept in a separate tank in the pet shop? The only way to stop the bullying is to take out the offending fish, give them away or give them their own aquarium!

Infrequent Water Changes

Partial water changes are necessary to remove a build up of nitrates. Although nitrates are much less toxic to the fish than nitrites or ammonia the levels can build up over time until a toxic level is reached. Partial water changes are the only way ro remove nitrates from your aquarium.

Adding Water Contaminated with Chlorine or Chloramines

Tap water is treated with either chlorine or chlorine and chloramines. Chlorine is easily removed by allowing the water to stand for a day or two but chloramines cannot be removed this way. If your local water authority uses chloramine you will need to purchase a water treatment chemical to remove it before you add the water to your tank.

Overfeeding

A major cause of problems, especially in beginner fish keepers. Food left over stays on the bottom of the tank and begins to decay producing chemicals toxic to the fish, This is especially likely to happen in a small aquarium. Overfeeding can also lead to death as the fish, not having a mechanisms to tell them when they are full, can eat until a swollen stomach causes death.

Remedies

If possible test the water for nitrites and ammonia. These levels should always be zero. If they are not perform a partial water change of about 20%. A good rule is to do a 10% water change weekly and a 30% water change monthly. if your problems are due to a build up of toxic chemicals this should improve the situation dramatically.

Never add any more food to the tank than the fish can eat in three minutes. If you suspect overfeeding use a syphon to clean the gravel and do a partial water change as above.

If overcrowding is a problem give away some of the fish or give them a new aquarium home.