云南盘鳇仔稚鱼发育的初步观察

摘要

为探究云南盘鮈(Discogobio yunnanensis)仔稚鱼发育过程,积累云南盘鮈基础生物学资料,为其规模化养殖提供科学指导,以人工孵化刚出膜的云南盘鮈仔鱼为对象,开展了其仔稚鱼发育研究.使用显微数码拍摄系统,定期观察云南盘鮈仔稚鱼各阶段的发育情况,并定性或定量描述其外部形态及内部结构特征.研究显示,在水温(20±0.5)℃ 的培养条件下,云南盘鮈初孵仔鱼体质量(0.012±0.001)g,全长(7.16±0.03)mm.卵黄囊呈长梨形,长(4.04±0.02)mm,高(1.35±0.02)mm.仔鱼出膜后第9天开始摄食,出膜后第28天卵黄囊消失,混合营养期长达19 d,推测该时期的存在有利于仔鱼与外界建立营养关系,降低早期发育阶段的死亡率.出膜后第45天鳞片出现,第80天鳞被完整,晚期仔鱼共历时17 d;另外,根据云南盘鮈自身特点将稚鱼期稍作调整,以出膜后第165天口吸盘发育完整作为稚鱼期结束的标志,稚鱼期共历时120 d.%In order to investigate the basic biological data of Discogobio yunnanensis larvae and juveniles and provide theoretical guidance for large-scale artificial breeding, we carried out an experiment at water temperature of (20±0.5) ℃ and observed the devel-opment of D.yunnanensis larvae and juveniles under digital camera system, described the external morphology and internal structure characteristics qualitatively or quantitatively. We found that the newly hatched larvae had the body mass of (0.012±0.001) g and the total length of (7.16±0.03) mm. The length and height of yolk sac were (4.04±0.02) mm and (1.35±0.02) mm, respectively. The lar-vae started feeding on 9th day and the yolk sac was absorbed thoroughly on 28th day after hatching. The stage of mixed nutrition las-ted 19 d. It is speculated that the existence of this stage was conducive to establishing nutritional relationship between larvae and the outside world, and reducing the mortality rate at early developmental stage of fish. The scales appeared and developed entirely on 45th and 80th day after hatching. The late stage of larva lasted 17 d. In addition, we made a little adjustment to the juvenile stage ac-cording to the characteristics of D.yunnanensis, taking 165th day after hatching as the sign of the end of juvenile stage when the suck-ing disc developed well. The juvenile stage lasted 120 d.