Effects of LED spectra on the growth and physiological mechanism of juvenile Sebastes schlegelii. Part I: Growth, feeding and digestion and metabolism

Light is a crucial and multifaceted ecological factor that profoundly influences fish feeding, growth, development, and physiological processes, either directly or indirectly. To examine how various LED spectra affect the growth, feeding, and digestion of juvenile Sebastes schlegelii, we conducted this study using juvenile Sebastes schlegelii specimens with an initial body length of (6.27 +/- 0.05) cm and an initial body weight of (7.56 +/- 0.17) g. In this experiment, 750 juvenile Sebastes schlegelii were carefully selected and placed into five distinct LED spectral treatment groups: green light (GL, lambda 525-530 nm), blue light (BL, lambda 450-455 nm), yellow light (YL, lambda 590-595 nm), red light (RL, lambda 625-630 nm), and white light (WL, lambda 400-780 nm). These fish were closely monitored throughout the study. The photoperiod was set at 12 h of light followed by 12 h of darkness (12 L:12 D), and the light intensity was maintained at 250 mW/m2. After a 60-day experimental period, we evaluated the growth performance, feeding intake, as well as the activities of digestive and metabolic enzymes. The findings indicated that juvenile Sebastes schlegelii exhibited improved length, weight gain, fatness, and feed conversion efficiency under the illumination conditions of GL, BL, and WL. At the same time, RL had a detrimental impact on the growth, development, and feeding performance of juvenile Sebastes schlegelii, resulting in reduced body length and weight, as well as the lowest fattening and feed conversion efficiency. Regarding digestive enzyme activity, juvenile Sebastes schlegelii reared under BL and YL conditions exhibited higher digestive enzyme activity. The GL, BL, and YL environments significantly increased the metabolic enzyme activity of juvenile Sebastes schlegelii, which reached a higher level by the end of the experiment. The results indicate that, when compared to other spectral environments, GL, BL, and WL were advantageous for the growth, feeding, hunting, digestion, and metabolism of juvenile Sebastes schlegelii. These conditions promoted healthy growth and a more favorable growth trend in juvenile fish. In contrast, RL hindered the growth of juvenile fish.