28th ANNUAL EASTERN FISH HEALTH WORKSHOP April 21-25, 2003 Rancid Food For Thought David J. Pasnik, Robert B. Duncan, Jr., and Stephen A. Smith Aquatic Medicine Laboratory, Department of Biomedical Sciences and Pathobiology, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061 Steatitis has been widely observed in mammals and only sporadically reported in fish.  This condition has been attributed to improper nutrition, and its incidence in fish may increase because cultured foodfish are increasingly maintained on a single-source diet.  Thus, fish become more susceptible to effects of food oxidation and dietary insufficiencies.  Subsequent malnutrition may be accentuated in newly cultured foodfish species for which dietary requirements have not been fully elucidated. Adult yellow perch, Perca flavescens,from an intensive aquaculture facility were submitted to the Aquatic Medicine Laboratory with chief complaints of chronic mortalities, external lesions, and abdominal distension.  Fish exhibited diffuse petechiae and ulcerations on the skin.  Skin and fin scrapes demonstrated a mixed bacterial population and rare fungal hyphae, while gill clips showed moderate telangiectasia and moderate mucus production.  Internal examination exhibited excessive amounts of firm, mottled reddish-brown-to-white adipose tissue filling the abdominal cavity and occasionally over-inflated swim bladders.  Bacterial cultures revealed mixed isolates of Aeromonas sp., Pseudomonas sp., Shewanella sp., and Vibrio sp. from the brain, posterior kidney, and skin lesions.  Histologic evaluation of sampled tissues demonstrated mild-to-moderate hyperplastic branchitis associated with filamentous bacteria among the gill lamellae.  Coelomic adipose tissue had coalescing granulomatous inflammation with extensive deposition of acid-fast material (ceroid/lipofuscin) in macrophages.  All other observed organs appeared normal.  Based on these clinical findings, a diagnosis of granulomatous steatitis with secondary bacterial infection was made. Return to 28th Annual Eastern Fish Health Workshop Return to Leetown Science Center Home Page