养殖军曹鱼稚鱼骨骼畸形研究

Skeletal Deformities in the Juveniles of Cultured Cobia (Rachycentron canadum)

关键词:  军曹鱼  稚鱼  软骨—硬骨双染色  骨骼畸形

Key words:  Rachycentron canadum  Juvenile  Double staining of cartilage and bone  Skeletal deformities

摘要:

本研究采用软骨—硬骨双染色技术对常规养殖条件下的军曹鱼(Rachycentron canadum)稚鱼全骨骼进行染色，观察并分析其骨骼畸形发生部位及相应的畸形类型。结果显示，在同一批次繁育的180个军曹鱼稚鱼(25日龄)骨骼标本中，有72个标本存在畸形情况，畸形率为40.00%。骨骼畸形类型共计22种，畸形率由高到低主要表现为米克尔氏软骨畸形、尾上骨缺失、脉棘分叉、基舌骨异位和尾上骨愈合等；所有骨骼畸形均未表现出显著可见的外部形态变化。但正常个体与骨骼畸形个体的全长存在极显著差异(P<0.01)。本研究表明，骨骼畸形对军曹鱼生长产生了影响。本研究为探索鱼类骨骼畸形的发生过程和原因、减少畸形率和优化苗种培育养殖条件提供了理论基础。

Abstract:

Cobia (Rachycentron canadum) is an important marine fish with marked potential for aquaculture in China. Skeletal malformations are fundamental problems that severely decrease the production efficiency and profitability of cobia aquaculture by affecting external morphology, growth, and survival. In this study, we documented the skeletal deformities in tank-reared cobia juveniles (25 days after hatching; n=180). Based on observations of cleared and double-stained specimens, skeletal deformities have been described. Overall, 72 of 180 fish were deformed (with a deformity rate of 40.00%) and 22 types of skeletal malformations were identified: Meckel’s cartilage deformity, basihyal deformity, basihyal allotopia, lowered hyoid arch, lordosis, vertebral deformity, bifurcated neural spines, bifurcated haernal spines, haernal spine fusion, cartilage redundancy, epural deficiency, epural fusion, epural deformity, hypural deficiency, hypural and parhypural fusion, hypural deformity, bifurcated pterygiophore, pterygiophore deformity, pterygiophore redundancy, pterygiophore allotopia, anal fin ray redundancy, and dorsal fin spine deficiency. Malformations were most common in the cranium (17.22% of specimens) and caudal fin (15.56%), and the skeletal deformities with the highest incidence were Meckel’s cartilage deformity (12.22%) and epural deficiency (7.78%). All fish with these skeletal deformities showed no visible morphological changes. In addition, a significant difference in total length (TL) was found between normal fish and all deformed individuals (P<0.01), individuals with cranial deformities (P<0.01), and individuals with caudal fin malformations (P<0.01). The TL of individuals with dorsal and anal fin deformities was significantly different to that of individuals with cranial (P<0.05) and caudal fin malformations (P<0.05). These results provide insights into the skeletal developmental process for optimizing cobia rearing conditions.