Signs Of Infection

Cotton wool like fungus growths occurring anywhere on the fish.

Fish Affected

Fish fungus, Saprolegnia sp. and Achlya sp., can affect all fish.

Details Of Infection

Fungi spores are naturally present in water. The fungi, like their land relations, are actually plants that grow and thrive on dead organic matter. Thus only damaged fish are susceptible and healthy fish will resist infection. Usually a graze or wound will attract fungus however sometimes a wound is due to infection by another parasite such as worms or flukes. In this instance both the fungus and the primary cause of infection must be treated. If left to develop, fungus will kill the fish.

Fungus is most often seen growing on infertile eggs. Infected eggs should be removed to prevent contamination of healthy eggs. In a breeding tank, Methylene Blue is usually added to inhibit fungal growth on infertile eggs.

Treatment

Chemical treatments such as Malachite Green are most efficient at eradicating fungus. Methylene Blue is an alternative but the chemical will stain silicone sealant and affects filter bacteria. In mild cases a strong (3%) salt bath can be effective. Good water conditions and a slight raise in temperature also suppresses attack.