A bulge on the side of a zebra dog's head and belly may be due to water drum disease, which is a disease that destroys the internal flesh and blood structure of the fish and causes abnormal growth of the side parts. The causative agent of water drum disease is unknown, and the incidence rate is not high, but the mortality rate is high.

The head symptoms of zebra dogs suffering from water bulge include enlarged belly, appetite at first, loss of appetite in the later stage, and finally It may float on the water or sink to the bottom of the box without moving. If you squeeze the abdomen with your hands, yellow fluid may flow out. The disease may last longer and may eventually lead to death. There is currently no effective treatment, so it is recommended to withhold treatment in this case.