The last time I tried to start an aquarium, all my fish died, what happened?

Although we believe anyone can succeed at keeping an aquarium, to maximize your chances of success you need to know a few basic things. If in the past you had problems with fish dying while starting an aquarium, the most likely cause was ammonia poisoning.

When you start an aquarium you are really building a mini eco-system. One of the most critical parts of this eco-system is a colony of bacteria that live in your filter and your gravel bed. The colony of bacteria helps break down fish waste in stages from ammonia to nitrite and then finally to nitrate. Ammonia and nitrite are toxic to fish while low levels are nitrate are ok.

Ammonia poisoning happens when you add too many fish before the bacteria colony in your new tank has had time to develop. The fish produce a large amount of waste in the form of ammonia and because there is an insufficient amount of bacteria to process the toxic ammonia, fish then die.

To avoid this problem make sure to do the following:

  • Seed your tank with bacteria either by purchasing a bacteria culture product like Seachem’s Stability, add some “aged” gravel, or take the filter sponge from an already established and healthy aquarium and put it in your new filter.
  • Start your tank with large amounts of fast growing plants.
  • Take your time adding more fish.
  • Never overfeed. It is a myth that you can feed a fish too much. You can, however, overfeed a tank. This means that any uneaten food will aid in the production of ammonia and nitrite, and we already know what that does to your fish. This is probably the number one cause of problems in the aquarium.