Studies on the essential fatty acid requirement of channel catfish, Ictalurus punctatus

Abstract

Two experiments were conducted to characterize essential fatty acid deficiency in fingerling channel catfish and determine the qualitative requirement of channel catfish for essential fatty acids. Supplementation of 1% ethyl linoleate, 1% ethyl linolenate or 1% ethyl linoleate plus 1% ethyl linolenate to tristearin or ethyl oleate based diets (5% total lipid) did not improve the growth rate of catfish to the level obtained by feeding a 2.5% corn oil plus 2.5% cod liver oil diet during a 12-week study. Fish fed the lipid-free diet or the tristearin or ethyl oleate diets had a higher level of eicosatrienoic acid in their liver polar lipids. The growth rate of catfish was effectively improved by supplementation of 1% n−3 highly unsaturated fatty acids to a tristearin based diet (5% total lipid). These data do not indicate whether linoleic and/or linolenic acid are essential for the catfish; the n−3 highly unsaturated fatty acids appear to be responsible for the enhanced growth.