has high economic value and vast market prospects because of its nutritional and delicious flesh and appealing body color. This experiment investigated the effects of light color on growth, skin color, and physiological indices of juvenile in a recirculating aquaculture system (RAS). The trial employed a single factor design of four light colors (red, blue, dark, and day-night) to raise juvenile (body weight, 64.2 g±1.1 g) for 94 d. As a result, the weight gain rate of fish in the day-night group increased by 28.6% and 39.2% compared with that in the dark and red light groups ( < 0.01), but no difference was observed compared with the blue light group ( > 0.05). The weight gain rate in the blue light group increased by 31.2% compared with that in the red light group ( < 0.05). Skin carotene content of fish in the day-night group exceeded that in the blue and dark light groups by 45.7% and 68.5%, respectively ( < 0.05), but no difference was observed compared with the red light group ( < 0.05). Skin carotene and melanin contents of fish increased and decreased at the same time, but by different amounts in the four treatments. Therefore, we defined this phenomenon as “synchronous but different magnitude”. Pepsin activity of fish in the day-night group increased by 48.0%-88.5% ( < 0.05) compared with that in the other groups. Fish in the day-night group had better immunity, assuperoxide dismutase and lysozyme activities were significantly higher than those in the other groups ( < 0.01), whereas malondialdehyde level was lower than that in the dark and red groups (-ATPase activity increased by a mean of 78.1% in the day-night and red light groups ( < 0.01). Trypsin activity was significantly higher in the blue light group than that in the red and day-night light groups by 34.3% and 21.8%, respectively (P. leopardus under day-night light had better growth, skin color, and physiological performance than those held under the other conditions. Blue light improved protein digestive ability and growth, and red light increased carotene content and nutrition absorption by fish. The “synchronous but different magnitude” phenomenon helped regulate and optimize fish skin color. These results suggest that the light color juvenile are exposed to in a RAS should be considered to optimize growth and skin color.