Fungus in Goldfish


Name of disease: Fungus

Other names: Cotton Wool Disease

Type of disease: Fungal (various species of aquatic fungi)

Occurrence: Very common, affects all types of freshwater fish.

Symptoms include: White, grey or brown cotton-wool like patches on fish's body and/or fins (can easily be confused with Columnaris disease). Goldfish eggs are also prone to fungus.

Caused by:

1. Damage to the slime coat on fish due to rough handling, wounds or other physical damage which allows free-floating fungal spores access to skin.

2. Secondary infection following attack by other diseases such as Ich, Finrot or Ulcers.

3. Sudden change of temperature, unhygenic tank conditions or poor water quality may increase likelihood of fish contracting fungus. Pond fish are more prone to fungal attack in spring following a sudden rise in temperature.

4. High quantities of decaying organic matter in the tank will increase number of fungal spores and make infection more likely.

Treatment: Remove affected fish to hospital tank if possible. Swabbing fungus patch with iodine may be sufficient to cure problem. If not, EITHER treat with fungicidal medication (e.g Jungle Fungus Eliminator in US, Anti-Fungus Remedy in UK) OR a .3% salt solution.

Precautions: Salt and medications affect the cycle so monitoring water quality during treatment is essential. If left untreated, fungus can spread very quickly and kill the fish.




Medications: Potassium Permaganate (pp), Medi-Gold, Melafix, Maracyn, Nitrofura-G, Chloramine T, and Parasite Clear (Jungle Labs).