Abstract:The effect of delayed feeding in early development stage on growth, survival and biochemical composition in tongue sole Cynoglossus semilaevis larvae was examined. Larvae were divided into four groups, each with 500 larvae (three replicates). At the water temperatures of 21~22 ℃ and salinity of 31.0, initial feeding of the control group with rotifer began at 3 days post-hatch (dph), the feeding of the other groups began at 4 dph (delayed feeding 1 day, D1), 5 dph (D2) and 6 dph (D3), respectively. The results showed that the mixed feeding stage for the larvae was at 3 dph. It was at 4 dph when the growth of larvae began accelerating. The yolk sac was almost completely absorbed at 5 dph, which suggested for an onset of complete exogenous feeding. After the 15d experiment, significant difference was observed only in dry weight between the control and the D1 larvae. The total length, dry weight, protein content and lipid content of D2 larvae were significantly lower than the control larvae (P<0.05). The survival rate of larvae decreased corresponding to the delay in initial feeding time. There was no significant difference found in mortality among all treatments within 4 days after mouth-opening. While 6 days after mouth-opening, the difference was much more significant. The morality of D3 larvae reached almost 100% at 10 dph.
