抄録
Rainbow trout reared with fat-free diet for three months, the posterior part of the fish body was observed getting discolored and hardened. The posterior fin was worn out and, in some extreme cases, the fin was observed almost disappearing leaving the terminal of spinal column. Many of the fish died. Diets containing 50 or 200 μg per g of body weight per day, of any of such fatty acid esters as ethyl linoleate (I), ethyl linolenate (II) and ethyl ester of polyunsaturated fatty acids (III) never caused the above symtoms. Of the above three diets III was the most excellent in the accumulation and efficiency of the diet with minimum mortality of the fish. II was the next and I was the last of the three. In each ester, 200μg of dose showed the better effect than 50 μg, though a further experiment may be necessary to determine the minimum requirement of these fatty esters. Remedial effect of the esters was observed on the fish of deficiency symptoms which had been reared with fat-free diet for two months. III was found most effective, followed by I, and II in this order.
