The nutritional disease of yellowtail Seriola quinqueradiata caused by feeding on raw sardine Sardinops melanosticta was diagnstically investigated by comparison with fish fed on sand lance Ammodytes personatus as a control. Fish fed on sardine showed retardation of growth, high mortality, and low feed conversion effciency. In the diseased fish, hematocrit value, serum albumin level, and serum lactate level were significantly lowered. The serum contained extremely large amounts of lipoperoxide, which specifically conjugated with lipoprotein of globulin fraction. The electrophoretic belavior of serum protein and liporprotein were considerably changed. Obvious pathological symptoms appeared in the kidney; necrosis of the tubular epithelia and numerical atrophy of the hematopoietic tissue, which would correlate to high ammonium-nitrogen and low urea-nitrogen levels in the serum. Nothing peculiar was seen in the spleen, gills, and digestive ducts.
These results of the diagnostic investigation revealed that the disease caused by sardine feeding was appreciably different from a nutritional one caused by anchovy feeding.