There are fungus treatments but most are not practical for pond situations. Your fish have what we call cold water fungus in our northern region. The fish with fungus are symptoms of stress. Fix the stressors and the fungus will not occur next year. I think this year you will have to wait for it to run its course. Most all fish with the fungus will eventually die. If you don't figure out what stressed the fish and fix it, the problem will occur again next year. The fungus spores are always present in natural waters.

When fish are stressed by scraping, handling, lack of proper feeding or nutrition and slime or mucous layer is removed or degrades from patches of skin/scales the area becomes infected with fungus growth. Ends of fungus filaments swell and burst open to release many more spores which can reinfect. ASAP Removal of infected fish reduces number of infecting spores in pond.


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