Effects of DHA-enriched live food on growth, survival and incidence of opercular deformities in milkfish (Chanos chanos)

The use of commercial enrichers to improve the nutritional quality of live food in larviculture of milkfish was investigated. Fish were either fed rot ifers cultured on Chlorella sp. and newly hatched Artemia nauplii (Control, Trt I) or rotifers and Artemia given DHA enrichment diets (DHA-treated, Tr t II). Results showed survival was significantly better (P < 0.05) in the DHA-trea ted fish than in the untreated fish after 25-day culture period. Although g rowth was not statistically different (P > 0.05) between the control and DH A-treated fish during the hatchery phase, extensive rearing of the postlarv ae (fry) in nursery ponds for another 60 days showed that DHA-treated fish exhibited significantly better (P < 0.05) growth than the untreated fish. O percular deformities in 85-day old milkfish juveniles were also significant ly lower (P < 0.05) in the DHA-treated fish than the control. Survival afte r nursery culture, however, was high for both treatments but not significan tly different (P > 0.05). The lack of a viable and reliable method of mass culturing copepods as live food in the hatchery makes the use of off-the-shelf commercial enrichment diets for rotifers and Artemia a practical option in the larval culture of milkfish. (C) 2001 Elsevier Science B.V. All rights reserved.