astaxanthin

:  a carotenoid pigment C₄₀H₅₂O₄ found in red- or pink-colored aquatic organisms (such as shrimp, lobster, and salmon) and the feathers of some birds that is used especially as a food coloring and dietary supplement Wild salmon attain their color by absorbing a carotenoid called astaxanthin from their krill-based diet, while farmed salmon eat fish feed supplemented with various sources of astaxanthin to enhance their grayish color. — Cook's Illustrated Astaxanthin is found in many marine animals, like shrimp and fish, and is also responsible for the pink color of flamingos that feed on crustaceans rich in the pigment. — C. Claiborne Ray