Effects of docosahexaenoic acid on growth, survival and swim bladder inflation of larval amberjack (Seriola dumerili, Risso)

The effect of docosahexaenoic acid (DHA) on the growth performance, survival and swim bladder inflation of larval Seriola dumerili during the rotifer feeding period was investigated in two feeding experiments. Amberjack larvae at 3day post hatching were fed rotifers enriched with (1) freshwater Chlorella (Chlo), (2) a mixture (2:1, v/v) of Chlo and DHA-enriched Chlorella (DHA-Chlo), (3) DHA-Chlo and (4) DHA-Chlo and commercial DHA emulsion, in triplicate for 7days. The average DHA contents of the rotifers were 0.0, 0.4, 1.0 and 1.9mgg(-1) DM respectively. The survival rate was improved by the enrichment of rotifers with DHA-Chlo alone, and DHA-Chlo and emulsion. Growth and swim bladder inflation of fish fed rotifers enriched with DHA-Chlo were significantly (P<0.05) improved, however, with increased levels of DHA further improvement was not found. DHA content in the larval whole body proportionally increased with the DHA level in the rotifers. These results suggest that DHA enrichment of rotifers is effective to improve the growth, survival rate and swim bladder inflation of amberjack larvae. The DHA requirement of amberjack larvae is estimated to be 1.5mgg(-1) on a dry matter basis of rotifers.