Combined effect of photoperiod and self-feeder on the growth performance of striped knifejaw, Oplegnathus fasciatus

Abstract

This two-factor experiment incorporating three photoperiods (12L:12D, 16L:8D and 24L:0D) and two feeding methods (manual and self-feeding) was carried out to determine their effect on the growth performance of striped knifejaw, Oplegnathus fasciatus. Thirty juveniles were stocked into each 300L tanks in triplicate for each treatment and fed a commercial diet for 10weeks. Two-way ANOVA revealed that both photoperiod and feeding method have significant effect on the final mean weight, weight gain (%) and feed efficiency (FE) (P<0.05); however, their interaction did not produce any significant effect (P>0.05). Although the growth parameters didn't have significant difference between manual and self-feeding in fish exposed to 12L:12D photoperiod (P>0.05), fish under other two photoperiods showed significant improvement under self-feeding system compared to manual feeding (P<0.05). Final mean body weights in fish under 16L:8D and 24L:0D were 119.7 and 124.0g at manual feeding; however, increased to 128.0 and 133.7g, respectively at self-feeding system. While two daily peaks of feed intake were observed in 12L:12D and 16L:8D photoperiods when self-feeders used, 24L:0D photoperiod showed only one morning peak. At the end, there was no significant difference in different stress indicators such as cortisol, glucose and total protein among the treatments (P>0.05). Finally, the results suggested that the extended (16L:8D) and continuous (24L:0D) photoperiods, and the provision of self-feeder could significantly improve the growth performance of striped knifejaw without changing the stress response. Statement of relevanceThis is the first report on the combined application of photoperiod manipulation and self-feeder on striped knifejaw, which revealed that the combination would help to improve the growth performance significantly. The indoor aquaculture industry, at least, will be benefited from the important insights achieved from this study to stimulate the growth performance of this commercially important species, which has great consumer demand in Japanese market.