If the newly bought koi fish jumps into the tank, you can add a cover to the fish tank so that they can't jump out. The reason why the fish jump out of the tank is that the environmental changes cause the fish to feel uneasy and want to jump out. Usually, as long as you rest for a period of time, the fish will recover. If there is any jar jumping, it means that there is something wrong with the environment. It is necessary to change the water in time, raise the water temperature, keep oxygenation and create a good growth condition.

1. Rest for three days: The newly bought koi should rest for three days first. The reason for resting is that the environment has changed, and it takes some time for fish to adapt to the new environment. During the rest period, you don't need to feed it, don't eat it after feeding it, and don't change the water, so as not to disturb it and affect its recovery.

2. Proper feeding: After three days of rest, the fish will not swim around, so you can feed some food at this time. Koi has a miscellaneous diet, and there are many things that can be fed. However, when it was first raised, it mainly chose animal feed, which it likes to eat and will not resist when feeding.

3. Prepare to change water: It is usually only after one week of feeding that koi fish can be changed for the first time. It should be noted that too much water should not be changed, otherwise the water quality will fluctuate, which will affect the adaptability of fish and be unfavorable to their health. Moreover, it is best to measure the water temperature before changing water to ensure that the temperature is consistent before and after.