大银鱼的胚胎发育及仔鱼习性

The embryonic development and habit of larvae in large icefish Protosalartx hyalocranius

采用Pixera Penguin 600CL数码照像机对大银鱼ProtosaIartx hyalocranius胚胎发育的各个时期及仔鱼的开口饵料、仔鱼养殖过程中的摄食行为进行了观察。结果表明:大银鱼受精卵在4～9℃下孵化全程约需852 h,胚胎发育经历了9个生理阶段共30个发育期;出膜后仔鱼平均体长为4.76 mm,全长为4.86mm;出膜后约20 d卵黄完全吸收;平游期鱼苗平均体长为5.85 mm,全长为6.09 mm。在显微镜下对不投饵养殖条件下的仔鱼进行观察,发现仔鱼早期(10～20 d)以浮游植物为开口饵料,20～40 d时可主动摄取轮虫,仔鱼对轮虫壳及休眠卵无法消化。

The embryonic development and initial feeding of larvae were observed in large icefish Protosalartx hyalocranius under a Pixera Penguin 600CL digital camera system.The fertilized eggs were hatched in 852 hours at water temperature of 4-9 ℃ and the embryonic development was divided into 9 physiological stages,namely 30 developmental substages.The newly hatched larvae had average body length of 4.76 mm and total body length of 4.86 mm.The yolk sac was exhausted about 20 days after hatching,and the fry with body length of 5.85 mm and total body length of 6.09 mm was found to swim normally.The larvae fed on phytoplankton as weaning food in the 10-20 initial feeding days under unfed condition,and began to feed rotifers actively 20-40 days after initial feeding.Microscopic observation revealed that the shells and resting eggs of the rotifers were not digested by the larvae.