Effects of natural and commercial diets on the fatty acid content of European grayling

Eicosaenoic acid (20 : 1 omega 9) and docosaenoic acid (22 : 1 omega 11) le vels were about 10 and 100 times higher in food pellets fed to cultured gra yling than in the insect larvae on which wild grayling fed. Among the PUFA, docosahexaenoic acid (DHA) was very high in the pellets, resulting in an u nnaturally elevated, and probably unbalanced, omega 3/omega 6 ratio of 7-13 in the cultured fish whereas the same ratio varied only from 4 to 6 in the wild fish. Despite very low DHA levels in the native food, wild grayling m uscle tissue contained relatively high amounts of DHA. DHA is probably not essential in the diet of grayling. (C) 1999 The Fisheries Society of the Br itish Isles.