Tank color affects growth, feed utilization efficiency, coloration, and biochemical composition of juvenile giant trevally (Caranx ignobilis Forsskål, 1775)

Tank color is an important environmental factor influencing aquaculture performance, but it remains poorly understood for juvenile giant trevally (Caranx ignobilis) under laboratory conditions. This study evaluated the effects of five different tank colors (white, blue, red, yellow, and dark grey) on growth performance, survival, feed utilization efficiency, body coloration, and biochemical composition of juvenile giant trevally. In a 28-day experiment, juvenile giant trevally with an initial mean length of 1.91 ± 0.03 cm and an initial weight of 0.24 ± 0.04 g were reared in tanks with different colors at a density of 1 fish/L, and each treatment was replicated three times. Results showed that fish reared in yellow tanks had higher growth rate, higher survival, and lower feed conversion ratio compared to those reared in white and blue tanks (p < 0.05). Fish reared in yellow and red tanks had significantly darker yellow body coloration and accumulated more carotenoids than those reared in white and dark grey tanks. Additionally, fish reared in yellow and red tanks had higher body protein content, whereas fish reared in white tanks had higher body moisture content (p < 0.05). These findings indicate that tank color could be an important factor in improving the rearing performance and skin pigmentation of juvenile giant trevally. Yellow tank color is suggested as a potential strategy to optimize juvenile giant trevally seed production in aquaculture.