Carotenoids are produced by algae, plants and certain fungi.
Feeding fish higher-level animals in the food web (like crustaceans or fish that predate on crustaceans) concentrates the carotenoids and brings out more and more color in the fish, specifically red.
Carotenoids are produced by algae, plants and certain fungi.
Feeding fish higher-level animals in the food web (like crustaceans or fish that predate on crustaceans) concentrates the carotenoids and brings out more and more color in the fish, specifically red.
And mercury right?
Mercury is more highly concentrated in higher-level organisms in a similar fashion, yes.
But mercury itself has nothing to do with coloring.