Fish illness is very distressing to see and it can be hard to know what is happening, why and how to solve it. This article will lay out the common ailments found in most tanks and ponds, what are the potential causes and how to treat your sick fish.

What is it? It is the process by which waste is converted from a very toxic substance called Ammonia (produced by fish waste) into the far less toxic substance Nitrate, which is removed during water changes when it builds up. Once the cycle is complete, ammonia and nitrite levels should be zero and nitrate is kept low by water changes. Learn more science!