EFFECT OF DIETARY-FAT LEVEL ON WEIGHT-GAIN, DIGESTIBILITY, AND FILLET COMPOSITION OF ATLANTIC HALIBUT

Two experiments were carried out to obtain information on the effect of dietary fat levels on juvenile (6-12 g) and larger (0.6-1.5 kg) Atlantic halibut (Hippoglossus hippoglossus). The juvenile halibut were fed dry diets containing 12% fat and 54% protein and 21% fat and 49% protein, respectively. The larger fish were fed moist diets formulated to be isonitrogenous (19-21% protein on a wet-weight basis), to contain equal amounts of carbohydrate (9-10%) and increasing amounts of fat (8, 12, 16 or 20%, respectively). Dietary fat level did not result in significant differences in weight gain for any of the two size classes of halibut. No significant effects of the various diets were seen for feed efficiency, chemical composition of fillets and livers or digestibility of dietary dry matter, fat and protein for the larger fish. Large individual variation was observed in all recorded data.