About Tropical Fish Disease

Most fresh-water aquarium fish come from the tropics. There they live in very clean water that is filled with the nutrients they need to stay healthy. When introduced to aquariums, many times, we must mimic those habitats by other means such as chemicals. Many times tropical fish suffer because of our good intentions.

Smaller Volumes of Water

One particularly difficult obstacle to overcome in regards to tropical fish being confined to aquariums is the small volume of water. No matter how large your aquarium might be, it can never match the volume of water found in the tropical habitats these fish come from. In the tropics these fish has large amounts of water in which to feed and leave its droppings in. Add to that the numbers of fish that might exist in an aquarium and you can see the problem. This waste contains microorganisms that also harbor parasites. In the closed environment of an aquarium, these microorganisms are not so easily avoided and they begin to multiply.

What Diseases can Tropical Fish Contract?

Some of the more common diseases include:

• Ammonia Poisoning. As the name suggests it comes from too much ammonia in the tank. Check water with an ammonia and nitrite test kit prior to adding fish. Traces of ammonia and nitrites must be nearly zero.


• Cataracts. This disease is characterized by white or grey material covering the eyes. These are fungal growths caused by too much ammonia or nitrates.


• Fungal Infections. White or cotton-like areas located on the fins or mouth or any injuries the fish as sustained. Again, this is a disease of poor water quality specifically related to ammonia levels.


• Ich. Probably ich is the most widespread tropical fish disease. Small white pimple-like growths occur on the fins. Ich is very contagious to other fish and the water must be treated to destroy the protozoa that cause the disease.


• Velvet. This disease resembles ich; however, the pustules are located on the body rather than the fins as is the case with ich. Poor water quality, chilling or stress caused in transport causes this disease.