Blueline Surgeonfish

Acanthurus nigroris

The Blueline Surgeonfish is a marine ray-finned fish belonging to the family Acanthuridae. It is characterized by its pale to dark brown body adorned with slightly irregular, horizontal, dotted blue lines. These lines are thinner than the brown spaces between them, creating a distinctive pattern. Additionally, blue lines are present on the head below the eye and on the gill cover, running parallel to the snout. A notable feature is the black spot at the posterior of both the dorsal and anal fins, with a diameter less than half that of the eye. The dorsal and anal fins also display horizontal reddish-brown bands with a slender blue margin, and the caudal fin has a thin white rear margin. This species can reach a maximum standard length of 18 cm. The Blueline Surgeonfish is found in the central Pacific Ocean, specifically around the Hawaiian Islands and Johnston Atoll. It inhabits various environments, including lagoons, seaward reefs, and areas with mixed sand, rock, and coral rubble. This species is typically seen in schools that can range from a few individuals to hundreds. It thrives in depths ranging from 2 to 20 meters, grazing on filamentous algae and feeding on plankton. Divers encountering the Blueline Surgeonfish can expect to see it in schools, actively swimming and grazing on algae. While the conservation status of this species has not been evaluated, it poses no threat to humans.