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

Abstract

The use of commercial enrichers to improve the nutritional quality of live food in larviculture of milkfish was investigated. Fish were either fed rotifers cultured on Chlorella sp. and newly hatched Artemia nauplii (Control, Trt I) or rotifers and Artemia given DHA enrichment diets (DHA-treated, Trt II). Results showed survival was significantly better ( P<0.05) in the DHA-treated fish than in the untreated fish after 25-day culture period. Although growth was not statistically different ( P>0.05) between the control and DHA-treated fish during the hatchery phase, extensive rearing of the postlarvae (fry) in nursery ponds for another 60 days showed that DHA-treated fish exhibited significantly better ( P<0.05) growth than the untreated fish. Opercular deformities in 85-day old milkfish juveniles were also significantly lower ( P<0.05) in the DHA-treated fish than the control. Survival after nursery culture, however, was high for both treatments but not significantly 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.