乌原鲤仔鱼摄食和饥饿耐受能力研究

Feeding and Starvation Tolerance of Yolk-sac Larvae of Percocypris mera

研究乌原鲤(Procypris merus)仔鱼早期培育过程的摄食特点和饥饿耐受力,为苗种规模化培育提供技术支撑。试验缸为玻璃烧杯(1 L),置于恒温水浴锅中;试验用水为经过24 h曝气的地下水,无天然生物饵料;水温20~22℃;仔鱼随机分为3组(摄食组、饥饿1组、饥饿2组),每组500尾仔鱼,每组设置3个重复,静水养殖;摄食组每日投喂3次丰年虫。结果显示,乌原鲤仔鱼5日龄开口摄食,初次摄食率15%,5~9日龄为混合营养期,8日龄初次摄食率达100%,并维持到14日龄;15日龄后呈下降趋势,在19日龄时降至45%,达到饥饿不可逆点。饥饿胁迫对乌原鲤仔鱼全长、体长、体高、肛前长、眼径等生长指标有极显著影响(P<0.01)。在水温20~22℃条件下,可在乌原鲤仔鱼6日龄开始投喂适口饵料,不迟于10日龄,生产中可根据实际情况观察乌原鲤仔鱼肠道贯通、卵黄囊消耗等情况,掌握仔鱼初次投喂时机。

In this study,we explored the feeding characteristics and starvation tolerance of yolk-sac larvae of Percocypris mera.At a water temperature of 20-22℃,newly hatched P.mera larvae were selected to study the effects of starvation stress on the growth,development,survival,yolk sac absorption,initial feeding rate and feeding intensity of P.mera larvae.The initial feeding time and point of no return(PNR)of P.mera larvae were determined based on the test results.It aimed to provide technical support for the large-scale breeding of P.mera.In March and April 2021,artificial breeding test of P.mera was carried out at the fish breeding and releasing station of Hongshui River,Guangxi Province.Newly hatched yolk-sac larvae of P.mera were randomly divided into three groups(feeding group,starving group 1 and 2),with each treatment run in triplicate and 500 individuals per group.The test fish in feeding group were fed with fairy shrimp three times daily and the test lasted util the death of all individuals in starving group 1.During the test,the growth parameters of P.mera in the feeding group and starving group 1 were observed each day.After feeding began,20 fish in starving group 2 were randomly selected each day and fed with fairy shrimp and the initial feeding rate and initial feeding intensity were recorded two hours after feeding.Results show that 5-9 day-old larvae were in mixed nutrition stages.The larvae of P.mera began feeding on day 5,with an initial food in⁃take rate of 15%,while the feeding rate of 8-day P.mera larvae reached the highest level of 100%.The high feeding rate was maintained until day 14 and then trended downrd.The 19-day-old larvae of P.mera reached the irreversible growth point.Starvation had highly significant effects on the growth indices of P.mera larvae,including full length,body length,body height,anterior anal length,and eye diameter(P<0.01).In conclusion,the larvae of P.mera have strong starvation tolerance.At a water temperature of 20-22℃,we recommend that the larvae of P.mera are fed from day 6 and no later than day 10.Mastering the first feeding time of P.mera larvae will improve the survival rate and support large-scale cultivation of the P.mera.