Study on the Adaptive Regulation of Light on the Stress Response of Mandarin Fish () with Re-Feeding after Starvation.

Light influences the stress response to environmental stimuli and feeding behaviors of and, thus, is an important regulator of normal growth and development. In this study, we first explored the important role of light on the digestive and stress capacity of by studying the changes in physiological and biochemical indicators of , taking the re-feeding after starvation as the constant environmental stimulus and the light intensity as the adjustable environmental stimulus. The activity of protease and lipase was generally higher in the stomach tissues than in the intestinal tissues, especially lipase, which was higher in stomach tissues under all light conditions, and the protease and lipase activity peaked in the stomach tissues of at a light intensity of 18.44 ± 3.00 lx and in intestinal tissues at 11.15 ± 2.01 lx, respectively, indicating that greater light intensity increased the digestive capacity of stomach tissues, whereas lower light intensity facilitated the digestive capacity of intestinal tissues. The tissues of the gill, stomach, and intestine had relatively high activity of stress-related enzymes, whereas the tissues of the brain, kidney, liver, and plasma samples had relatively low activity of enzymes. Collectively, the results show that light intensity at 11.15 ± 2.01 lx promoted digestive capacity in the intestine and enhanced the anti-stress ability of in response to stress induced by re-feeding after starvation. These findings should prove useful for artificial breeding of .