What is the best treatment for a fungus infection on koi carp?

The best treatment for a fungal infection in koi carp typically involves the use of antifungal medications, such as formalin or potassium permanganate. It’s crucial to isolate the infected fish to prevent the spread of the fungus and maintain good water quality to aid healing. Additionally, improving overall tank conditions and ensuring a balanced diet can support the fish's immune system during recovery. Always consult a veterinarian or aquatic specialist for specific diagnosis and treatment recommendations.