Experiments were conducted to find out suitable dietary lipids in the practical feed for Nile tilapia, Oreochromis nilotius. Soybean oil, corn oil, fish oil or cuttlefish liver oil was mixed in the diet and tested. The best weight gain and feed efficiency were obtained from the fish fed soybean oil or corn oil, both rich in 18 : 2n-6. But the growth rate of fish fed diet with fish oil or cuttlefish liver oil were inferior. The levels of 20 : 3n-9 in the total lipid were not different in all tested lipids, but that in the polar lipid of the fish oil or cuttlefish liver oil were lower than that in the soybean oil or corn oil. Thus, vegetable oil such as soybean oil or corn oil, rich in 18 : 2 n-6, were suitable as dietary lipid for Nile tilapia. Unlike other fish species, fish oil or cuttlefish liver oil showed no essential dietary value for this species.