The blue tang (Acanthurus coeruleus) is a species of surgeonfish found in coral reefs worldwide. Blue tangs, like all surgeonfishes, use these spines to defend against predators. They erect the sharp spines in an effort to make themselves harder to swallow or to inflict injury on their predators.
Blue tangs are herbivores, and they actively browse the surface of coral reefs, searching for their favorite algae. Though larger individuals sometimes browse by themselves or in pairs or threesomes, small to medium adults often form large groups and swim long distances, browsing along the reef surface throughout the day. With overfishing of their main predators, they are thriving more than ever.
According to Oceana, juveniles live among dead coral rubble or in mangrove forests in more protected waters and move to the open reef surface as they mature. Adult blue tangs are solid blue (or almost dark purple), while juveniles are solid yellow.
Blue tangs are consumed by humans only rarely when caught in artisanal fish traps, but bright yellow juveniles are targeted quite significantly in some locations for the private aquarium trade. Even so, scientists have assessed the blue tang’s population status and have found it to be a species of least concern.
Dory, a popular movie character from the movies Finding Nemo and Finding Dory, is a species of blue tang called the powder blue tang.