Effects of variation in essential fatty acids in fish feeds on nutritive value of freshwater fish for humans

Effects of variation in essential fatty acids in fish feeds on nutritive value of freshwater fish for humans. Several marine fish species are rich in n-3 polyunsaturated fatty acids (PUFA) such as eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA). This is attributed to the lipid composition of plankton. There is strong evidence suggesting that consumption of fish containing high levels of these fatty acids is favourable for human health and has a particularly beneficial effect in preventing cardiovascular diseases. However, freshwater fish species can also serve as a valuable source of essential fatty acids. Compared with marine fish species, freshwater fish contain, in general, higher levels of C18 PUFA, but also substantial concentrations of EPA and DHA. In addition, the fatty acid composition of freshwater fish species is characterized by high proportions of n-6 PUFA, especially linoleic acid and arachidonic acid. Therefore the ratio of total n-3 to n-6 fatty acids is much lower for freshwater fish than for marine fish, ranging from 1 to about 4. However, keeping freshwater fish such as salmonids and common carp on diets containing high amounts of fish oil results in marketable fish with substantial levels of n-3 PUFA. (C) 1997 Elsevier Science B.V.