The effect of diet on the fatty acid composition of several species of fresh water fish

Summary Four kinds of fresh water fish were captured in the young stage, maintained on a low‐fat diet for about two months, and either continued on that diet or transferred to test diets containing 10% cottonseed or menhaden oil for about five weeks. The fish were then sacrificed, and their total body fatty acids were examined for relative amounts of 2, 3, 4, 5 and 6 double bonds. It was found that no significant change from the natural diet occurred in the fatty acids on the low‐fat or cottonseed oil diets while on the menhaden oil diet the fatty acid composition changed to resemble the composition of that oil. These changes differed from those of the marine mullet in that the body fat of the latter lost much of its naturally occurring polyunsaturated acids, when placed on the low‐fat regimen, and regained it on the menhaden oil diet.