1. Change water in time: The first thing to do when the fins of carp are rotten is to change water. Whether caused by bacteria or parasites, changing water can reduce its content and improve water quality, thus reducing the possibility of fish disease deterioration. Generally, water change is once every 1-2 days, and each time the water change is about one quarter, and at most, it should not exceed one third. Too much change is easy to stimulate the fish body.

2. Raise the temperature: After changing the water for koi, the next thing to do is to raise the temperature, but it only needs to raise it by 1-2 ℃. Proper warming can accelerate the metabolism of fish and stimulate its resistance, so that it can heal itself. However, it should be noted that heating up also has side effects. For some bacterial diseases, heating up will also accelerate the reproduction of germs.

3. Adding salt properly: In order to alleviate the side effects caused by temperature rise, it is necessary to add a proper amount of sea salt to the water body, and the general concentration is about three thousandths, and the highest concentration cannot exceed five thousandths. By adding salt, the osmotic pressure of water can be increased, which can reduce the immersion of water from the body surface, thus reducing the possibility of germs invading fish.

The rot fins of brocade carp are usually caused by poor water quality, large number of bacteria in water, or fish injury. In view of the poor water quality, the best way is to change the water regularly, usually once a week, and don't change more water every time, otherwise it will stimulate the fish. In view of the growth of bacteria in water, some drugs can be used to sterilize, but the dosage should be controlled to avoid the large number of beneficial bacteria being eliminated.