Longfin Damselfish

Longfin Damselfish, Juvenile

The Longfin Damselfish has a brownish-gray to dark brown body, which often appears with a yellowish tint on its head. Its long dorsal and anal fins extend past the base of its tail, with the anal fin featuring a blue edge. Juveniles are dark yellow with vibrant blue lines on their heads and a distinctive black spot encircled in blue on their dorsal fin.

This Damselfish is known for its aggressive and territorial behavior. It is an algae farmer, defending a small area where it cultivates and eats algae. It has a relationship with small shrimp called Mysids, which live within the algae farms. The Damselfish protects the Mysids, and in return, the shrimp’s waste fertilizes the algae, improving the food supply for the damselfish. Females lay sticky eggs on a clean surface, and the male fertilizes and guards them, fanning them to keep them clean and oxygenated until they hatch.