Tank Color Impacts Performance of Cultured Fish

Tank color impacts marine fish larval performance, as dark tanks appear to provide contrast that allows larvae to better visualize live and artificial prey. While tanks can be fabricated in any color, commercially available on–growing systems are generally black, green, or dark and light blue. Anecdotal information suggested that certain juvenile fish perform better in tanks with black sides and sandy colored bottoms. To determine whether tank color impacted performance of juvenile fish we examined the effect of black, green, red, dark, and light blue colored tanks on the short–term growth and feed efficiency of summer flounder and growth, feed efficiency, body composition of Nile tilapia. Cortisol response was also examined for both species. Tank color did not affect growth performance of flounder or tilapia although fish maintained in red–colored tanks returned better percent increases in weight. Differences (P < 0.05) in feed conversion efficiency were observed for summer flounder held in red tanks. Plasma cortisol levels in summer flounder ranged from 1.39–3.71 ng cortisol per ml, compared to 12.7–94.4 ng cortisol per ml plasma for tilapia. Lowest cortisol levels (P < 0.05) were detected in flounder and tilapia reared in red–colored aquaria. Background color had no effects on tilapia fillet composition.