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In this study, the impacts of various illumination intensities on growth, digestion and metabolism as well as antioxidant enzyme dynamics of Takifugu rubripes (0.03 ± 0.01 g) were investigated. Activities of alkaline phosphatase (AKP), acid phosphatase (ACP), pepsin (PPS), alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), superoxide dismutase (SOD), and total antioxidant capacity (T-AOC) were measured. Juveniles were reared under four degrees of illumination intensities: 50 mW/m2, 250 mW/m2, 500 mW/m2 and 750 mW/m2, at a constant photoperiod (12D:12 L). Samples were collected at days 7, 14, 21, 28, and 35. After 35 days, the 750 mW/m2 light intensity was found to have significantly increased the final body weight, which was 1.1 ± 0.005 g. On day 35, PPS activities of T. rubripes juveniles in the 750 mW/m2 sample group were significantly low when compared to those of the 250 mW/m2 group while AKP activities in the 750 mW/m2 group were significantly higher than those of the 50 and 500 mW/m2 groups (p 0.05). Even though they were relatively lower, there were no significant differences in SOD activities in the 250 mW/m2 group relative to the 500 and 750 mW/m2 groups. On day 35, high light intensity (750 mW/m2) resulted in stress responses that were characterized by T-AOC activities, and activity values were significantly lower than those of other groups (p

Photoperiod is one of the important environmental factors, which have important effects on the early growth and development, survival, metabolism and immune system of larvae. In the present study, Takifugu rubripes larvae were exposed to four different LED photoperiods: 8 L:16 D, 16 L:8 D, 20 L:4 D and 24 L:0 D from −1 to 30 days post hatching (DPH). We measured growth, activity of pepsin (PPS), lipase (LPS), alanine aminotransferase (ALT), aspartate aminotransferase (AST), and non-specific immune enzyme activity of alkaline phosphatase (AKP), and acid phosphate (ACP), superoxide dismutase (SOD), Catalase (CAT), glutathione peroxide (GSH-PX), total antioxidant capacity (T-AOC) at 1, 5, 10, 15, 20, and 30 DPH. The results showed that there was no difference in the effects of photoperiod on the growth within 18 DHP, while 20 L:4 D had a positive effect on the growth of the larvae after 19 DPH. The effect of photoperiod on digestive enzymes did not show obvious regularity. Compared with photoperiod, the changes of some digestive and metabolic enzymes were mainly affected by exogenous food (LPS, ALT, AST changed obviously after feeding Artemia). On the 30 DPH, the AKP of 8 L: 16 D and 24 L: 0 D groups was significantly higher than that of the other two groups, which indicated that 8 L: 16 D and 24 L: 0 D lighting might cause stress to fish body and lead to the increase of AKP. GSH-PX in newly hatched fish at 24 L:0 D was significantly higher than that in other groups. Photoperiod had no significant effect on the enzyme activity of PPS, LDH, ACP, CAT and no obvious pattern was found. Overall, our results suggested that 20 L:4 D promoted larval growth after 19 DPH and shorter photoperiods can be used to save electricity before 18 DPH of Takifugu rubripes larva.