The pigment melanin contributes to the black edges (b) on the anal fin that are a sign of dominance, while pterins account for the red and yellow colors (a) on the anal fin, and signal health. Carotenoids on the caudal fin (c) indicate that the fish is eating well. Brighter, more-intense colors are associated with better mating success.

Photo by L. Brian Stauffer; graphic by Julie McMahon

illinois.edu Built-in-billboards: Male bluefin killifish signal different things with different fins CHAMPAIGN, Ill. - They help fish swim, but fins also advertise a fish's social standing and health. In a new study, researchers report that for the male bluefin killifish (Lucania goodei), each colorful fin presents its own messages to other fish.