It converts linoleic acid (the precursor of omega-3 fatty acid family) into alpha-linolenic acid Zthe parent fatty omega-3 fatty acid family) by adding another double bond at the third carbon from the methy end. The desaturation and elongation of alpha-linolenic acid to synthesise DHA occur either in. some animal planktons or in the livers of small fish eating those phytoplaktons. The amount of omega-3 polyunsaturated fatty acids increases along the food chain. The geographical location, season, aswell as the genetics of those fish determine the variable content of DHA and other omega-3 fatty acids. Fish oil of some marine fuish living in cold-water regions contains high amount of DHA especially when compared