Fungal infections are among the most common diseases seen in tropical fish. Because fungal spores are found in all fish tanks, they can quickly create problems in stressed, injured, or diseased fish. The most common type of fungus is called Saprolegnia which causes ‘cotton wool’ like growths to appear on the fins, gills, mouth and eyes of infected fish. This disease normally affects fish that are suffering from other illnesses such as White Spot.
Cause: Fungi are present throughout most aquariums, but certain conditions increase the possibility of fungal infections including:
• Tropical fish that are injured or have other diseases. • Introduction of new fish that may already be infected. • Dead fish or large amounts of decomposing organic material in the tank.
• Poor aquarium water quality.
The spores of fungus can become infectious to other fish that are weak or injured.
Treatment: It is important to immediately remove any fish suspected of having a fungal infection to a quarantine tank for treatment.
A traditional method to cure tropical fish fungal disease was to place the infected fish in a salt bath.
Anti-fungal medicines are usually the best option to fight the infection. Treat the infected fish with Malachite Green in a separate tank for 30 seconds at a strength of 60 mg/L. Keep the fish under observation for 2 or 3 days as fungus can sometimes regrow. Repeat treatments may be necessary.
In some instances if multiple fish infections are present, the entire tank should be treated, but if individual infections are present, treating the fish in a separate quarantine tank is preferable.
Tanks with fish that have reoccurring fungal infections need to be examined for tank hygiene, filtration and water quality.