If you change water, you can only change half! Leave half of the raw water. . I believe someone has a mineral water bottle at home. Connect the water and put it in the refrigerator for freezing. When the water temperature is higher, take out a bottle of frozen mineral water and put it in the fish tank to solve the problem! But pay attention to the temperature and don't catch a cold on fish! Our ecological fish farm has always been like this. I hope I can help you!