Farmed salmon require synthetic astaxanthin to develop their characteristic pink color; the welfare and health implications of this dependency reveal broader issues in intensive fish farming.
Astaxanthin supplementation in farmed salmon is a welfare-relevant indicator of the distance between natural salmon biology and intensive aquaculture conditions. Wild salmon obtain carotenoids from their natural diet in quantities sufficient for flesh coloring, immune function, and antioxidant protection. Farmed salmon in artificial pellet systems require synthetic supplementation to replicate what their natural diet would provide. The health benefits of adequate carotenoid supplementation are real, meaning that adequate supplementation actually serves welfare. However, the underlying issue is a farming system that produces fish whose nutritional baseline requires supplementation to approximate natural health status.