PLASMA BIOCHEMISTRY AND DISEASE RESISTANCE IN YELLOWTAIL FED A NON-FISH MEAL DIET

Yellowtail Seriola quinqueradiata fed a non-fish meal diet and control fish fed a standard fish meal diet were reared in neighboring net-cag es under the same natural environmental conditions. The growth and foo d consumption of the fish fed the non-fish meal diet (NFM fish) were s imilar to the fish fed the control diet (control fish). Mortality due to a natural infection with Pasteurella piscicida occurred among NFM f ish, but not among control fish during 55 days of feeding experiment. Plasma total cholesterol, free cholesterol and phospholipid of NFM fis h were significantly lower than those of control fish. This result ind icates that the decrease in the levels of plasma lipid components may be a good indicator of reduced disease resistance in yellowtail.