The optimal feeding frequency of large yellow croaker (Pseudosciaena crocea, Richardson) larvae

A 30-day feeding experiment was conducted to determine the effects of feeding frequency on the growth, survival and specific activity of digestive enzymes in large yellow croaker larvae (13days after hatch) with an initial weight of 4.08±0.1mg. Feeding frequency of 2, 4, 8 and 12 times daily as four treatments were evaluated against a control without feeding in triplicate tanks. The fish were fed to satiation each time. The results showed that treatment of 8 meals per day (meals d^-1) had significantly higher survival (P<0.05) compared with other treatments. Specific growth rate (SGR) in 8 meals d^-1 treatment was significantly higher than those in 2 meals d^-1 or 4 meals d^-1 treatments (P<0.05), but was not significantly different from that in 12 meals d^-1 treatment (P>0.05). No significant differences in coefficient variations (CV%, P>0.05) of fish larvae body length were observed among the treatments, but there was a significant negative dependency between CV and feeding frequency (CV=-0.1476×feeding frequency+17.55, R²=0.9352). Both crude protein and crude lipid in fish larvae significantly increased with increasing feeding frequency. There were no significant differences in fatty acid composition of fish larvae. The specific activity of trypsin, both in pancreatic and intestinal segments, first significantly increased (from 2 meals d^-1 to 8 meals d^-1) and then kept at a constant level (from 8 meals d^-1 to 12 meals d^-1). There were no significant differences in specific activities of amylase among dietary treatments. Results of this study suggest that the optimal feeding frequency was 8 meals d^-1 in the culture of large yellow croaker larvae.