Non-infectious Diseases
These are caused by environmental, nutritional, and genetic factors. Some of the environmental factors are high amounts of ammonia, high levels of nitrite, low level of oxygen, or toxins in the aquarium. The main nutritional factor leading to such diseases is a deficiency of vitamins. The setup of the tank, or the makeup of the diet will have to be changed to remedy these conditions. Genetic abnormalities can't be controlled, and are, by definition, a random aberration.