Abstract
Observations were made on eight outbreaks of a new fungus disease among fry of Salmo gairdneri, Onchorhynchus rhodurus and O. masou in several trout farms located in Giru prefecture from December, 1974 to May, 1975. Moribund fry were characterized with a distended abdomen and a heavy growth of mycelia in the abdominal cavity and in visceral organs. No growth of mycelium on the surface of the body was observed in most moribund fish. Mortalities due to the disease were estimated to be 10-20%.
