杂交鳢仔鱼饥饿试验及不可逆点的确定

利用人工孵化的杂交鳢初孵仔鱼,在水温(26±1)℃条件下进行其饥饿试验并确定仔鱼的初次摄食不可逆点(PNR)。结果表明,杂交鳢仔鱼孵化后第2天开始摄食,进入混合营养期,此时卵黄囊缩小至原来的1/2,与油球一同继续被仔鱼吸收;孵化后第7天卵黄囊和油球被完全吸收,混合营养期为5d。杂交鳢仔鱼最高初次摄食率出现在孵化后第6天,此时卵黄囊已吸收完全,油球有残留。当初次摄食率降至最高初次摄食率的50%时,仔鱼进入不可逆期,不可逆点出现在仔鱼孵出后的第7～8天。

Starvation and Point of No Return in Hybrid Snakehead Larvae

Under the water temperature of(26 ± 1) ℃,the starvation trial and the definition of the point of no return(PNR) for the larvae of hybrid snakehead were conducted.The results showed that the larvae began to feed on the second day after hatching.At this time the yolk was exhausted 1 /2,with the oil globule continued to be absorbed,and were all absorbed on the seventh day after hatching.The period of mixed nutrition was from 5 days.The tiptop initial feeding rate of hybrid snakehead larvae occurred on the sixth day after hatching when the yolk was absolutely absorbed and the oil globule was still remaining.The initial larval feeding rates fell to 50% of the tiptop initial feeding rate and the larvae entered the PNR,which appeared on the 7-8 days after hatching.