Nutritional steatitis (yellow fat disease) in cultured silver catfish (Rhamdia quelen) associated with rancid feed

Abstract

Nutritional steatitis (yellow fat disease) caused by vitamin E (vit E) deficiency is typically associated with diets high in unsaturated fatty acids or/and low levels of vit E. This work describes, for the first time, an outbreak of nutritional steatitis in cultured silver catfish (Rhamdia quelen) in Argentina. Necropsy, histopathology, bacteriology and molecular studies of the affected fish were performed. In addition, peroxide level and vit E concentration of the fish feed were measured. Affected specimens had firm, yellowish-brown dermo-hypodermal nodules located in the adipose fin and dorsal region of the body. Histologically, lesions consisted of fat necrosis and multifocal granulomatous lobular steatitis, primarily affecting the subcutaneous and intermuscular adipose tissue, and occasionally, the coelomic fat. Feed analyses revealed a high level of peroxide value (41.2 meq/kg), indicative of rancid feed, and low concentration of vit E (2.7 IU/Kg). In this case, fish had been fed rancid food with inadequate value of vit E, leading to the development of nutritional steatitis caused by vit E deficiency.