Abstract
Histopathological study was made on cultured striped jack, Caranx delicatissimus with yellow fat disease. The diseased fish were collected at a fish farm on Shikine Island, Tokyo in May, 1989. These fish showed black discoloration on the body surface and were emaciated. The adipose tissues in the abdomen and the inner side of the operculum had changed to a yellowish color, with discoloration and atrophy of the liver. Histologically, steatitis, fat necrosis, multinucleated syncytium formation, deposit of altered lipids, small granuloma formation and deposit of ceroid-like lipopigments in macrophage centres (MC) were observed in the adipose tissues. Lipopigments similar to those found in the adipose tissues were also observed in MC formed in the liver, in the intra-muscular connective tissue of the trunk muscle, in the lamina propria of the pyloric caeca and the intestine, and under the endothelium of the sponge layer of the cardiac muscle. Ceroid-like lipopigments were also found in the cytoplasm of the hepatic cells and melano-macrophage centers in the spleen and the kidney. Hemolytic anemia and myopathy of the trunk muscle were also found.
From the results, it is suggested that the morbid state of this disease corresponds to that of the yellow fat disease reported in many species of mammals.
