An obscure disease of rainbow trout

An annul mortality among Rainbow Trout (Salmo gairdneri) has plagued the Shelton Hatchery of the Washington State Department of Game for the last several years. No infectious agent could be isolated from the moribund fish, but histopathologica1 changes in the liver of 1-month-old fish suggested the presence of a toxic substance. Scoliosis in 3-month-old fish suggested a possible deficiency in vitamin C. With this background in mind, we designed studies to determine the nature and source of possible toxicants and the role of vitamin C deficiency in the etiology of this disease.