1. Reason: Zebrafish's belly rot may be caused by injury, although they are gentle and will not actively attack other fish. But they swim faster, and if there are decorations in the fish tank, it is easy to scratch the internal organs.

2. Treatment: Breeders need to transfer injured zebrafish to a new container to prevent other fish from attacking them. Then use potassium permanganate solution or oxytetracycline medicated bath to avoid wound deterioration.

1. Reason: The rotten belly of zebrafish may also be caused by bacterial infection caused by poor water quality, which is mainly caused by infrequent water change or new fish in fish tank carrying bacteria.

2. Treatment: Breeders need to transfer zebrafish to a new fish tank to avoid infecting other fish. And change the water immediately to ensure the clean water quality. It is better to install another filter to slow down the deterioration of water quality. Usually, water should be changed once every 5-7 days, and the amount of water should be controlled at one third of the total amount of water.

1. Reason: Zebrafish belly rot may also be caused by parasites, which may be carried in food or bred in water.

2. Treatment: The breeder first prepares a separate container for zebrafish, and then fishes them out of the water to clean up their belly decay. Finally, they are given a medicated bath with insecticidal drugs, and some crude salt is added to the water where they live to inhibit the growth of bacteria.