密斯特黄彩鲶仔、稚、幼鱼的生长与发育研究

在水温22～24℃,pH7.0左右的人工培育条件下,对密斯特黄彩鲶(Mystus sp.)仔、稚、幼鱼的形态特征和生长发育进行了观察与研究。密斯特黄彩鲶的鱼苗发育分为卵黄囊期仔鱼期(初孵至第5天)、晚期仔鱼期(第6～10天)、稚鱼期(第11～20天)和幼鱼期(第20天以后)。初孵仔鱼平均全长5.12 mm,卵黄囊体积1.63 mm3;仔鱼第3天开始摄食,第5天卵黄囊被完全吸收,鱼苗主要外部器官主要集中在晚期仔鱼阶期和稚鱼期内形成。仔鱼在饥饿状态下最高初次摄食率出现在出膜后第6天,为84.0%,其饥饿的不可逆点则为出膜后第8天,第8天以后即进入不可逆PNR期,至第11天绝大部分饥饿仔鱼死亡。

Study on growth and development of larva, juvenile and young fish of Mystus sp.

At the water temperature of 22～24 ℃ and pH around 7.0,the growth and development of larva,juvenile and young fish of Mystus sp.were observed.The results showed that development of this species could be divided into four phases,including pre-larva(from hatching to the 5th day),post-larva(the 6th day to the 10th day),juvenile(the 11th to the 20th day) and young fish(after the 20th day) respectively.The first hatching larvae were only 5.12 mm long with a yolk-sac of 1.63 mm3.The larvae began to eat on the 3rd day and yolk-sacs were fully assimilated on the 5th day after hatching.The exterior organs developed mainly in the stage of late-stage larva and the largest inital feeding rate of larvae was 84.0% which appeared on the 6th day and the point-of-no-return was on the 8th day after hatching.From then,the unfed larvae entered into the stage of PNR and most died on the 11th day.