Paracanthurus

Paracanthurus is a genus of marine ray-finned fishes in the family Acanthuridae, the surgeonfishes. It is a monotypic genus, containing only the species Paracanthurus hepatus, commonly known as the blue tang, regal tang, or hippo tang.

The species has a laterally compressed body with a relatively small head. Adults are primarily blue, typically with a dark patch near the caudal peduncle and a bright yellow caudal fin. Dorsal and anal fins are often edged with lighter tones, giving the fish a distinctive appearance that varies with age and health.

Paracanthurus hepatus is native to the Indo-Pacific region, from East Africa and the Red Sea to Polynesia. It inhabits coral reefs and adjacent lagoons, commonly at depths of about 2 to 40 meters, where it can be found on seaward reef slopes and feeding fronts.

Ecology and behavior: It is primarily herbivorous, feeding on algae and biofilm. The species is diurnal and may occur singly or in small schools, sometimes forming larger aggregations around abundant food sources. Spawning is typically broadcast, occurring in the vicinity of reefs.

Relationship to humans and conservation: The blue tang is popular in marine aquaculture and the aquarium trade, requiring large, stable systems and high water quality. The IUCN lists Paracanthurus hepatus as Least Concern, reflecting its wide distribution and continued export for trade. It has also gained prominent pop culture recognition as Dory in the animated films Finding Nemo and Finding Dory.