The rotten body of carp usually does not heal itself. There are many cases of rotten body, which may be caused by the deterioration of water quality. In view of this situation, it is necessary to change water in time to keep the water body clean and hygienic. It may also be bacterial infection. At this time, it is necessary to isolate the sick fish in time to avoid mutual infection, and at the same time, it is necessary to treat them with drugs. If you change it too much water, it can also cause it to rot, so you must control the amount of water changed at ordinary times, which cannot exceed one third of the total amount.

1. Water quality deteriorates: Usually, koi fish rot because of the deterioration of water quality. The water for fish farming should be changed regularly, otherwise the number of harmful bacteria in the water will increase, and ammonia nitrogen and other substances will accumulate slowly, which is harmful to the health of fish. When changing water, pay attention to the same temperature of old water and new water, so that fish can adapt.

2. Bacterial infection: Bacterial infection can also lead to rotten tail and body of koi fish. This situation is usually due to the fact that the equipment and food put into the cylinder are not disinfected, and the environment in the cylinder is not good, resulting in a large number of bacteria breeding. If you want to avoid bacterial infection, you should do a good job of disinfection, especially live bait, which must be disinfected and fed.

3. New water stimulation: If too much water is changed for koi fish, the new water will also stimulate the fish body, which will lead to its rotten tail and rotten body. Usually, the water should not be changed too frequently, and it can be changed every five to seven days. The amount of water should not exceed one third of the total amount each time, and it is usually enough to change one quarter or one fifth.