The carp has erythema like bleeding, so it needs to be properly heated for observation. If the situation worsens, it needs to be changed with water and salt, and treated with drugs. If it recovers slowly, there is no need to worry. There are many cases of bleeding, which may be infected with bacteria or viruses. This kind of bleeding is difficult and usually needs to be treated with drugs. Besides, it may also be caused by environmental discomfort, which can be recovered after a few days of rest.

1. Bacteria: Bacterial bleeding is usually caused by the deterioration of water quality, and the oxygen content in water body is relatively low, thus accelerating the reproduction of bacteria, and the fish will get sick. Usually you can change the water, improve the water quality, and install a germicidal lamp at the same time, which can also effectively kill all kinds of bacteria.

2. Virus: Viral bleeding is usually caused by rhabdovirus, and the color of sick fish will become dim. At the same time, blood spots will appear around eyes, and there will be learning spots in muscles and intestines. If the situation is serious, it will even lead to anemia of fish.

3. Fighting: If fish fight in the tank, they may also be bitten and bleed. Therefore, before polyculture, we must know the situation and see if we can raise it together. Even if it is the same kind of fish, some of them are aggressive, so we should pay attention to isolation.

4. Environment: Environmental changes can also cause fish bleeding, such as water temperature fluctuation or excessive ammonia nitrogen in water, etc., which will make fish feel uncomfortable and then have stress reaction. If you want treatment, you need to add some anti-stress drugs such as vitamin C.