High-Hats are a small fish, usually between 6 and 9 inches, that can occasionally be found on coral reefs in the middle western Atlantic Ocean, in the Caribbean, the Gulf of Mexico, Florida and the Bahamas. High-hats are typically black and white or dark brown and white.Young high-hats typically live in rocks and coral hidden from predators. Generally they inhabit reef areas. High-hats are carnivorous fish that feed on crabs, shrimps and small invertebrates.This species of fish can live with other types of small fish, as they are not aggressive.

As a juvenile, its diet consists primarily of plankton. Adults are omnivorous and feed on plankton, but will also graze on algae. Spawning occurs during late afternoon and evening hours. This event is indicated by a change in color from a uniform dark blue to a pale blue. The fish is important for coral health as it eats algae that may otherwise choke it by overgrowth. Paracanthurus hepatus has a royal blue body, yellow tail, and black "palette" design. The lower body is yellow in the west-central Indian Ocean. It grows to 12 in. Adults typically weigh around 600 g (21 oz) and males are generally larger than females.