How do you treat fungal infection in fish?

Fish are removed from the water they appear to have a “slimy” matted mass growing out of the skin and scales. Use the 100mg/ litter strong malachite green solution to clean the lesion and apply a waterproof cream. (1956) reported that Ichthyosporidium is a fungus, but it manifests itself internally.

How long does it take for a fish fungus to heal?

This depends on how bad the problem is to start with. By using King British Fin Rot & Fungus Control there should be an improvement in 4-5 days. Due to fish having open wounds it is very important to keep water quality pristine, to prevent secondary infection taking place.