What makes farmed salmon pink? Astaxanthin. This vibrant pigment in the carotenoid family (which also includes beta carotene) is used as a feed ingredient in aquaculture to produce salmon that mimics wild salmon in color. It’s also used in shrimp farming.
Astaxanthin is produced by algae and other aquatic microorganisms and is thought to help protect against ultraviolet rays from the sun. Crustaceans (like krill and shrimp) that feed on algae store the pigment in their shells; in turn, fish (like wild salmon and trout) that eat the crustaceans (or the algae) store it in their skin and tissue. Humans get it primarily from seafood. The astaxanthin used in fish farming is either natural (from algae) or synthetic.
Astaxanthin is essential for the health of farmed aquatic animals, the aquaculture industry says—and, no doubt, it is essential for improving the appearance and thus the market value of the fish. Research, mostly in animals and test tubes, has shown that astaxanthin acts as an antioxidant and helps reduce inflammation—but whether it provides meaningful health benefits for people who consume it in seafood remains to be proven.
Bottom line: According to the European Food Safety Authority, the use of astaxanthin in amounts allowed for farmed salmon and trout is safe for consumers. Astaxanthin is also used as a colorant in many foods, where it is “generally recognized as safe” by the FDA. Don’t take astaxanthin supplements, however, which are touted to fight heart disease, prevent cancer, ease joint problems, slow aging, and do just about everything else. There’s no solid science to support any of these claims, and the safety of long-term use is unknown.
Also see Wild Versus Farmed.