White sardinella (Sardinclla albella) and Malabar thryssa (Thryssa malabarica) are underutilised small pelagic fatly fish species, available in large numbers in the North-Western coast of Sri Lanka. In the present study, seasonality of (he lipid and fatty acid composition of
these two fish species was determined. The seasonal variation of lipid content was studied
through out the two year period starting in 1994 and the fatty acid composition was studied over a one year period starting in 1995. The amount of lipids was extracted by standard Bligh & Dyer method and the fatly acid composition was determined by gas chromatography. In white sardinella, the higher contents of lipids were recorded in November and February-March. Malabar thryssa also recorded the two high values, February and September -
November. The minimum content of fat was observed around May for both species. The variation pattern of the fat content in experimental species exhibited similar individual patterns for both years. In both species, the saturated fatty acids and monounsaturated fatty acid were found to increase and polyunsaturated fatty acids (PUFAs) were found to decrease from February to March. The highest amount of n-3 PUFAs, 30.9% and 28.1%, were recorded in August for white sardinella and malabar thryssa respectively. The study showed the eicosapentaenoic acid (FPA, C 20:5 w3) and the docosahexaenoic acid (DMA, C 22:6 vv3) to contribute nearly 85 - 90% of the total omega-3 fatty acids. In most months the recorded EPA and DHA values were almost similar. However in May, DHA was 18.3% whereas EPA was 7.3%. The variation of fatty acids was higher around April - May. The changes in fat content and its fatty acid composition could be due to the biological changes of the body during the spawning season. Higher contents of lipids as well as omega-3 fatly acids during August - January indicated the suitability ol the season for commercial hsh oil production Irom the above
species.