Causes for fish to lose scales and rot:

1. Poor water quality. The reason why fish bodies can ulcerate is usually caused by poor water quality.

2. Water temperature stimulation. Large changes in water temperature will cause certain stimulation to the fish, causing its body to rot.

3. Bacterial infection. When a fish is infected with bacteria, it will also cause its body to ulcerate, but before that, it is often injured before the bacteria can invade the wound.

Methods to prevent fish from losing scales and rotting:

1. Change the water regularly. Be sure to change the water regularly, usually every five to seven days. If the water quality is maintained well, it can be changed every two months.

2. The water temperature is constant. During the daily feeding process, it is best to install a heating rod in the tank to maintain the temperature and prevent the water temperature from rising and falling, which is detrimental to the health of the fish.

3. Disinfect frequently. You must be careful at ordinary times to prevent the fish from being injured. Anything that goes into the tank needs to be disinfected or it can introduce bacteria into the tank.