Lipid nutrition in fish

Abstract

1. 1. Two main forms of neutral lipid are available to fish in the natural environment, namely triacylglycerols and wax esters. 2. 2. There is evidence that triacylglycerols can be hydrolysed completely to free fatty acids and glycerol in the gastro-intestinal tract and absorbed as such. Fatty alcohols resulting from wax ester hydrolysis are oxidized to the corresponding acid and thereafter follow pathways of fatty acid metabolism. 3. 3. Polyunsaturated fatty acids in fish tissues are predominantly of the ω3 series. 4. 4. Fatty acids of the ω3 series have essential fatty acid activity for fish. Some species have the ability to convert linolenic acid (18:3ω3) rapidly to longer chain polyunsaturated acids (20:5ω3, 22:6ω3) that have full essential fatty acid activity. Other species lack this ability and the polyunsaturated ω3 acid must be supplied preformed in the diet for maximal growth and freedom from pathology.