Changes in fatty acid profile during larval development of freshwater prawn Macrobrachium rosenbergii (de Man)

The fatty acid profile of Macrobrachium rosenbergii (de Man) larvae grown u nder hatchery conditions was studied during development from larval stage I to IX. The larvae were reared under a 'modified static green water' system with a modification in which the tanks were not seeded by green water at t he beginning of culture period. Feeding with newly hatched Artemia nauplii started at stage II with five or six Artemia per larva, which was then grad ually increased to 60 organisms per larva at stage IX when the study was te rminated. In general, fatty acid composition changed during larval developm ent, with the greatest variations observed from stage I to stage III. Monou nsaturated fatty acids constituted the major moiety of fatty acids of stage I whereas polyunsaturated fatty acids were the dominant fatty acid class i n later developmental stages. Moreover, polyunsaturated fatty acids were do minated by n-6 series in stage I and by n-3 series for the rest of the larv al stages. The major fatty acids of the stage I larvae were palmitic (16:0) , oleic/vaccenic (18:1) and linoleic (18:2n-6) acids, whereas for the rest of the larval stages, palmitic (16:0), stearic (18:0), oleic/vaccenic (18:1 ), linolenic (18:3n-3) and eicosapentaenoic (20:5n-3) acids were the promin ent fatty acids. Although decreases in total saturated fatty acids and mono unsaturated fatty acids were observed, polyunsaturated fatty acids tended t o increase during larval development. Unlike penaeid larvae, M. rosenbergii larvae appeared to have sufficient capability to convert palmitic (16:0) a cid to stearic (18:0) acid. Moreover, dietary linoleic (18:2n-6) and linole nic (18:3n-3) acids appeared to be converted to arachidonic (20:4n-6) and e icosapentaenoic (20:5n-3) acids to meet larval demand for such highly unsat urated fatty acids respectively.