CHANGES IN FATTY-ACID COMPOSITION OF COD LARVAE IN MASS-PRODUCTION

The changes of eicosapentaenoic acid (EPA) and docosahexaenoic acid (D HA) in total lipids were compared between fed and unfed cod Gadus macr ocephalus larvae during development. The EPA and DHA contents in 100 g of larvae on dry basis were different. The EPA content increased whil e the DHA content markedly decreased in the fed larvae till 20 days po st-hatch. On the other hand, the DHA content was almost constant in th e unfed larvae, however, the EPA content was reduced. Up to 5 days pos t-hatch, polar lipids notably decreased compared to the neutral lipids of the unfed larvae during the fasting period. It was also found that the mass mortality of fish coincided with a decrease in DHA level of live foods offered during the feeding period. In other words, the desc ent of DHA in the fed group of cod larvae was clearly related to the D HA levels in rotifers. Therefore, enrichment of the live initial foods with DHA is important for improving their dietary value, which in tur n promotes the normal growth of larvae.