Marine fish typically require n-3 HUFA for optimal growth
and health, usually in quantities ranging from 0.5-2.0% of
dry diet. The two major EFA of this group are eicosapentaenoic
acid (EPA: 20:5n-3) and docosahexaenoic acid
(DHA:22:6n-3). Freshwater fish do not require the long
chain HUFA, but often require an 18 carbon n-3 fatty acid,
linolenic acid (18:3-n-3), in quantities ranging from 0.5 to
1.5% of dry diet. This fatty acid cannot be produced by
freshwater fish and must be supplied in the diet.