LIPID AND FATTY-ACID COMPOSITION OF MILKFISH (CHANOS-CHANOS FORSSKAL) GROWN IN FRESH-WATER AND SEAWATER

The lipid and fatty acid compositions of the various organs of milkfish fed with a, invariant diet and reared in seawater (SW) and freshwater (FW) were determined using column chromatography and gas chromatography. Phospholipid content of the gills, kidney, liver, intestines and depot fat was higher in SW than in FW while the organs from fish in FW had higher contents of neutral lipid. Fatty acid patterns of total lipids in the liver, intestines and depot fat of milkfish reared in FW and SW were similar. There were marked differences in fatty acid patterns of gills and kidney. The proportions of saturated to unsaturated fatty acids in gills and kidney were lower in SW than in FW. Likewise, the ratio of n-3 to n-6 fatty acids and total polyunsaturated fatty acids (PUFAs) of gills and kidney were higher in SW than in FW. The fatty acid patterns of the phospholipid fractions showed that SW-reared milkfish have higher total PUFAs, especially of the n-3 fatty acids, than the FW-reared milkfish not only in gills and kidney but in all organs examined. The differences in lipid and fatty acid composition reflect a physiological response to the salinity in which milkfish were reared.