1. Gill disease: The diseased fish have slow movement, loss of appetite, dull body color, black head and white gills, which can be treated with nitrofurazone. You can also use potassium permanganate, formalin, salt and other treatment.

2. Cottonmouth disease: The muzzle of the diseased fish grows with white cotton-like hyphae like velvet, which makes it difficult for the diseased fish to eat, swim slowly and weakly, and even die. The diseased fish can be bathed with penicillin or 10ppm oxytetracycline solution.

3. Scaly disease: The scales of the diseased fish open like pine cones, the base of the scales is edematous and congested, and the base of the fins is full of translucent or blood-containing bodies in severe cases. Salt, nitrofurazone, antibiotics can be used. After treatment, smearing piyanping on the affected area has a better effect.