Add 1 tablespoon of salt per 5 gallons of water. Keep the tank as clean as possibile, rinse filters vacume gravel. If you can get some methylene blue give the fish a 30 min bath in 5 gallons of tank water add 1 teaspoon of meth blue and 1 tablesponn of salt. Return the fish to the main tank. See how that works. It's diffacult to tell weather this is a fungus or parasitic. Let me know if that helps.
