Studies on feeding rhythm and daily feeding amount of larval Epinephelus coioides

The daily feeding rhythms of fish were classified into four groups, named daytime feeding, night feeding, morning-dusk feeding and rhythmless feeding. In order to characterize the daily feeding rhythm and daily feeding amount of larval Epinephelus coioides, the fifteen-day-old larvae (4.86±0.38mm,total length) were used for study. The obtained results were as follows: experiments consisted of natural day-night group(control group), continuous light group and continuous dark group, the daily feeding amounts of rotifer were 142/larva, 156/larva, 47/larva respectively and the amount of daytime feeding were 91.3%, 80.5% and (71.7%) of that of total daily feeding amount, respectively. In the control group, an apparent feeding peak appeared at 14:00 PM. Similarly, in the continuous light group, the feeding peak presented at 16:00-18:00 PM. By contrast, in the continuous dark group, apparent feeding peak did not exist. In the evening, the feeding incidence of the continuous light group was higher than that of control group, in contrast with this, at the daytime, the feeding incidence of continuous dark group was much lower than that of control group. In the continuous light group, daily feeding amount increased slightly and it was 109.9% of that of control group, however, in the continuous dark group, daily feeding amount decreased obviously and it was 33.1% of that of control group. Taken together, our results showed that the feeding rhythm of larval Epinephelus coioides was identical with the daytime feeding. The feeding behavior of larval Epinephelus coioides had close relationship with light.