Experimental starvation on Cichlasoma managuense larvae and determination of point of no return

Under water temperature of (281) ℃, a starvation trial was conducted on Cichlasoma managuense larvae to determine the point of no return (PNR) and to study the effects of delayed initial feeding on the survival and growth of the fish. The results show that the larvae begin to feed on 4th day after hatching, and the mixed nutrition stage lasts for 3 d. The larvae come into endogenous nutrition stage at 7th day, in which the yolk-sac is absorbed completely. The initial larval feeding rate reaches only 15% at the beginningand 100% at 6th day, but decreases rapidly since 9th day. The PNR occurres at 9th~10th day after hatching. The survival is not obviously affected by delaying initial feeding for 1~3 d but drops significantly when the delay is more than 4 d. Under absolutely hungry condition, the total length of the larvae has positive growth in 0~8 d but then changes to negative growth. The difference is not significant in the total length of the larvae (12-day old) delayed initial feeding for 1~3 d (P0.05), but is very significant when the delay is more than 4 d (P0.01). The optimum initial feeding time for the larvae is within 3 d after their mouths open.