It is ok to treat the rotten mouth of ornamental fish with yellow powder. Yellow powder, also known as furacilin, is a common ornamental fish drug, which has a killing effect on a variety of bacteria and fungi, so it is a versatile drug, which can prevent and treat many diseases. There are two uses of yellow powder, one is to pour it directly into the tank and change the water the next day. Another is to prepare a special container to give sick fish a medicated bath alone, so as not to affect other healthy fish.

1. Fighting bites: Ornamental fish have rotten mouths, which are usually bitten by fighting. Although fish have no teeth, it is also very fierce to bite with the same kind. One of the common ornamental fish is called kissing perch, which is also called kissing fish. They kiss and fight. Generally, if fish are found to fight, it is best to keep them in isolation to avoid serious injuries.

2. Bacterial infection: If the ornamental fish is infected with bacteria, it will also cause its mouth to rot. This kind of situation often doesn't only rot the mouth, but the body, fins and other parts will rot to varying degrees. Therefore, it should be treated in time after discovery. Besides changing water, heating up and adding salt, it can also be soaked with drugs.

3. Deterioration of water quality: Deterioration of water quality will also affect the health of fish, causing it to rot its mouth. At ordinary times, we should pay attention to changing water, which should be changed every five to seven days, and every time we change water, we should not exceed one third, so that the water quality is maintained well and the fish will naturally not get sick.