Observation on the embryonic development of Changfeng silver carp

The embryonic development characteristics of Changfeng silver carp were studied at the water temperature(24±1)℃.The results showed that the fully mature eggs were spherical,semi-floating and (1.55±0.05)mm in diameter.After water absorption,the egg membrane swelled,the average egg diameter was(5.10±0.40)mm and without oil globule.It took(28.5±1.0)h from fertilization to hatching-out with the average accumulative temperature of(685.0±62.3)℃·h.The cleavage of fertilized eggs of Changfeng silver carp has belonged to discoidal cleavage.The embryonic development process could be divided into 7 stages,including fertilized egg stage,cell division stage,blastula stage,gastrula stage,neurula stage,organ formation stage and hatching stage.They contained eighteen developing phases,whose characteristics were described in detail.