七带石斑鱼仔鱼摄食习性的观察

Observation of the larval feeding habits of seven-band grouper Epinephelus septemfasciatus

关键词:  七带石斑鱼  仔鱼  摄食习性

Key words:  Seven-band grouper  Larvae  Feeding habit

摘要:

在人工育苗条件下，采用轮虫与牡蛎受精卵两种开口饵料，3种不同的投喂方式：开口单喂轮虫(A)、开口单喂牡蛎受精卵(B)、开口将牡蛎受精卵和轮虫混合投喂(C)，分析对比不同饵料对仔鱼开口效果。通过观察5日龄仔鱼日摄食与4~20日龄仔鱼消化道饱满度的变化，探讨仔鱼摄食习性及光照与摄食的关系。结果发现，七带石斑鱼孵化开口后，投喂3d牡蛎受精卵者比直接投喂轮虫对仔鱼生长有明显的效果；10日龄前，B组在全长、肛前距、口裂宽方面都大于A、C两组，B组全长的特定生长率为4.969%，分别是A、C两组的2.5与2.4倍，生长速度最快；5日龄仔鱼在09∶00~10∶00与13∶00~14∶00时间段，有两个明显的摄食高峰期，光照强度分别为720~1 018 lx与865~923 lx；4日龄仔鱼其饱食率较低，只有40%达到了3级摄食量，4~10日龄的仔鱼饱食率波动幅度较大，10日龄后开始逐渐上升，13日龄后基本可以达到100%。

Abstract:

Effects of two first-feeding diets(rotifers and fertilized oyster eggs) on the early stage larvae of seven-band grouper Epinephelus septemfasciatus were analyzed and compared with three different feeding modes (A. rotifers, B. oyster eggs, C. mixture of oyster eggs and rotifers) under artificial rearing conditions. Through observations on the feeding situation of 5 dph (day-post-hatching) larvae and gastrointestinal fullness of 4~20 dph larvae, the larval feeding habits and the relationship of light and feeding were discussed. We found that treatment B, which was fed with oyster eggs for 3 days,grew much better than treatment A, which was fed with rotifers only.The specific growth rate of total length in treatment B was 4.969%, which was 2.5- and 2.4-fold of treatments A and C, respectively. Before 10dph, total length, anal distance, and mouth width in treatment B were greater than the other two treatments. Two obvious feeding peaks were found at 9∶00~10∶00 and 13∶00~14∶00 for 5 dph larvae. The light intensity was between 720~1,018 lx and 865~923 lx respectively. The satiation rate of 4dph larvae was lower, in which only 40% reached the Ⅲ level in food intake. Satiation rate of 4~10dph larvae fluctuated, and it began to rise at 10dph, reaching 100% at 13dph.