Effects of delayed initial feeding on growth and development in jade perch Scortum barcoo larvae
PAN De-bo, ZHU Xin-ping, CHEN Kun-ci, LI Kai-bin, ZHEN Guang-ming , LUO Yu-jiang
1. Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510380, China; 2. College of Aqua- life Science & Technology, Shanghai Fisheries University, Shanghai 200090, China
Abstract: The effects of delayed initial feeding on food consumption, survival and growth were studied in jade perch Scortum barcoo larvae. The larvae exhausted the yolk at age of 4 days, then entered the period of mixed nutrition at water temperature of 24.5 - 27.8 ℃. The oil globules were absorbed completely in 6 day larvae which entered the exogenous nutrition. The larvae began feeding at the age of 3 days, with initial feeding rate of 97% two hours after feeding. However, the initial feeding rate was 100% , 90% , 67% , 30% and 0% two hours after feeding when the initial feeding was retarded 1 day,2 days,3 days, 4 days and 5 days, respectively. The point of no return (PNR) occurred 4 days after feeding. The 9 day old larvae had survival rate of 85%, 60%, 22. 5% and 0% (death) when their initial feeding was retarded 1 or 2 days, 3 days, and 4 days, respectively. At the same feeding peri gin the there was no significant difference in total body length and body length when the larvae were retarded to befeeding between the 3 day delayed initial feeding group and the control group, but significant difference between 4 and 5 day delayed initial feeding groups and the control group, indicating that the optimum initial feeding time was within 3 days after the larvae opened mouth.