条石鲷早期发育阶段鳍的分化

Differentiation of fin during early developmental stages of the rock bream Oplegnathus fasciatus

条石鲷仔稚鱼在室外水泥池进行培育,培育水温24-28℃,盐度28-32,pH7.6-8.4,对条石鲷早期发育阶段鳍的发育、分化进行了观察.结果表明:初孵仔鱼奇鳍鳍褶起始于头部,绕过尾部,终止于肛门;3日龄仔鱼出现胸鳍;8日龄仔鱼脊椎末端下侧出现放射丝;12日龄仔鱼脊椎末端开始上翘,腹鳍基形成;15日龄仔鱼胸鳍出现软条,背鳍、臀鳍在支鳍骨上方的相应位置分化出软条,尾鳍由圆形转变为截形,腹鳍形成2枚软条;20日龄仔鱼背、臀、尾鳍软条出现分节,腹鳍形成4枚软条,透明,无色素,尾鳍呈长截形,鳍中部略有内凹;30日龄稚鱼各鳍鳍条数目已发育完全,尾鳍鳍条出现分支,胸鳍和尾鳍还未有色素分布,背、臀鳍的鳍棘部已全部出现色素,软条部分还未完全着色素,腹鳍已全部着色素;40日龄进入幼鱼期,外部形态和成鱼相似,各鳍鳍条发育完全.条石鲷仔稚鱼胸鳍长与全长呈直线回归关系,且胸鳍长随日龄的增加而增长,呈指数关系.条石鲷各鳍的发育时序依次为胸鳍、尾鳍、背鳍、臀鳍、腹鳍.

The ontogeny of the fin on larvae of Oplegnathus fasciatus during early developmental stages was observed.Larvae were nursed in outdoor cement tanks at 24-28 ℃,salinity 28-32,and pH 7.6-8.4.The median fin-fold of 0-day-old larvae fish,which originated from the head to the tail,ended at the anus.Pectoral fin appeared in the 3 days after hatch（DAH） larvae fish.When the larvae fish was 8 DAH,the underside of the end of vertebra thickened.The end of vertebra warped up and the base of ventral fin began to develop on the 12 DAH.On the 15 DAH,the fin ray was found at pectoral fin,and the other fin rays were formed at the pterygiophore of dorsal fin and anal fin.Meanwhile,the rounded caudal fin became truncatus,and 2 sloft rays appeared at ventral fin.In the 20 DAH,the dorsal,anal and caudal fins commenced segmenting,and 4 transparent and non-pigmented fin rays were formed at the ventral fin.The caudal fin was long truncatus and slight concave.When the fish was 30 DAH,each fin ray was fully developed,and the fin rays of anal fin branched.The ventral pectoral and caudal soft rays were not pigmented yet,but the fin spines of dorsal and anal were already pigmented.The fin rays and ventral fins were partly and fully pigmented respectively.With all fin rays completely developed,the fish was turned into young fish in the 40th day,and shape was similar as adult fish.Relationship between length of the pectoral fin and total length was linear regression of O.fasciatus.Growth increased with the day.Pectoral fin of O.fasciatus formed the earliest,and then caudal fin,dorsal fin,anal fin,ventral fin.