Fungus is a secondary infection which is commonly found on a fish suffering with fin rot, mouth rot or ulcers. The fungal spores are always present in the pond, but will only affect a fish whose immunity has dropped due to stress.

Fungal infections resemble white or grey cotton wool, sometimes slimy looking, growing from the fish’s body, usually around the area of the rot or ulcer. The Fungus will usually clear up once the main infection has been treated, after which the pond should be partially water changed and the whole pond should be treated with an anti fungal remedy.