1. Reason: The body ulceration of carp may be caused by vaccinia, and the cause of this disease is bacterial infection. After the onset of vaccinia, koi fish first appeared some white spots, and when it was serious in the later period, the white spots would appear mucus and rot.

2. Solution: Breeders need to change water for sick fish first to ensure clean and refreshing water quality. Then use chloramphenicol and other drugs to treat sick fish, stick to it for about a week, and the rotten place will be improved. At this time, you can no longer use drugs, so long as you insist on changing water and disinfecting regularly, koi can be cured.

1. Reason: Carp may get mildew skin disease due to body ulceration. The main cause of this disease is that trauma is not treated in time, and finally the affected part is infected with bacteria. In the early stage of mildew skin disease, a layer of white hair will grow first, and in the later stage, when it is serious, the white hair will rot.

2. Solution: The breeder should first fish out the sick fish, clean it with salt water, and wash off all the white hairs on the surface of the sick fish. After washing, apply 0.1% malachite green solution. Finally, soak in potassium permanganate solution for about 15 minutes.

1. Reason: Koi fish may also suffer from water mold because of body ulceration, and the main cause of this disease is poor water quality. Koi has serious pollution to water quality. If the breeder changes water frequently, there will be more bacteria in water quality.

2. Solution: Breeders need to change water immediately to ensure clean water quality. Then use potassium permanganate solution to take a medicated bath for sick fish, and the medicated bath time should not be too long, but should be controlled within 15 minutes.