Fish Diseases – Fungal


When fish are ill do not feed them. Sick fish will not be eating and this uneaten food can cause further harm if not scooped out of the pond.


Fish Fungus is commonly known as Fuzzy Fish or Cotton Wool Disease, as the fungus looks like a cotton-like growth on the skin or fins. Fungal spores and fungi are common in ponds during spawning and if the pond is poorly maintained. Fungus can take action when the fish is in poor health, from either rough handling (This can be from spawning or handling of the fish resulting in damaged slime coating), poor water conditions or damaged tissues from wounds from previous disease or attacks from birds or cats. 


  • Abnormal Behaviour
  • Open Sores
  • White, Brown, Greenish or Gray Cotton-like growths on body. 
  • Bruised-looking and reddish tints to eyes, gills and fins. 


  1. The first thing to do is a Water Test. This will help to establish if the fish’s ill health is due to poor water conditions. If there are other problems in the water, such as high Ammonia or Nitrite levels, then you will need to do a
     partial water change before dosing with any treatments. 
  2. Treat the pond with Pondcare Pimafix or Pondmax MediMax. These treatments can be combined with Salt, which will help to restore the protective slime coating of the fish.
  3. If you had fairly poor water conditions from poorly maintained water you can use products such as Pond-Zyme, Eco-Fix or Lysofoss on a regular basis to help keep the pond clean. Lysofoss if good as it helps to control bad bacteria, reduce disease and stress and can control phosphorus, ammonia and nitrogen levels, and it is a completely natural treatment. Doing this combined with well oxygenated water will help prevent diseases.