丝鳍圆天竺鲷的繁殖习性、胚胎发育和胚后发育观察

Copulation, embryonic and post-embryonic development of Sphaeramia nematoptera

本文以丝鳍圆天竺鲷(Sphaeramia nematoptera)为研究对象,观察记录了其繁殖习性以及胚胎发育和胚后发育的过程。研究结果表明:丝鳍圆天竺鲷的繁殖活动由雌鱼主导,在凌晨1点至3点交配,产卵受精后由雄性口孵,产卵间隔期为11~18d,无季节性。雌鱼单次产卵3126~4882粒,受精卵近圆球形,卵径(720±10)μm,内有数颗油球;在水温(27.0±0.5)℃条件下,受精卵经过卵裂期、囊胚期、原肠期、神经胚期、器官形成期到出膜需187h。丝鳍圆天竺鲷胚后发育分为仔鱼期、稚鱼期、幼鱼期和成鱼期,初孵仔鱼全长(2.8±0.1)mm,口裂高度(0.202±18)mm,孵化后第二天仔鱼开口摄食;孵化后24d鳍条形成,身体出现两条黑色条带,结束浮游阶段,进入稚鱼期;孵化后50d鳞片完全形成,体色斑纹等外形特点与成鱼相同,进入幼鱼期;孵化后360d性腺发育成熟,具备生殖能力。

The copulation behavior,embryonic and post-embryonic development of Sphaeramia nematoptera were investigated in this study.The results showed that the mating behavior was dominated by females,mating between 1:00 and 3:00 am,and the reproductive cycle was 11~18 d without seasonal fluctuations.The release of eggs by female were 3126~4882 at a time,which were incubated by the male’s mouth.The fertilized eggs were suborbicular,(720±10)μm in diameter,with several oil globules inside.It took 187 h for a fertilized egg to be hatched under(27.0±0.5)℃.The embryo development process included Cleavage,Blastocyst,Gastrulation,Neurula and Organ formation stages.The post-embryonic development could be divided into juvenile stage,larval stage,juvenile stage and adult stage.The whole length of the first hatchling was(2.8±0.1)mm,the height of the mouth cleft was(0.202±18)mm,and the juvenile opened its mouth to feed at the second day after hatching.Fins began to form and two black bands appeared on the body when ending the floating stage and entering the larval stage 24d after hatching.Scales were fully formed 50d after hatching and the body color and markings as well as other appearance characteristics were similar to the adult fish,which indicated that the fish entered the juvenile stage.Maturation of gonad was achieved 360d after hatching.