The typical size is between 30 and 60 cm, but it can grow to almost 1 m. It has been observed as far north as Maryland and as far south as Brazil.

[3] Usually found between 3 and 80 m deep, it swims over reefs and sandy areas, where it feeds on algae by scraping it with its teeth fused into a beak.

Their main source of food is algae, which they scrape from coral and other hard substrates using their beak.

[6] In addition to herbivory, evidence suggests that midnight parrotfish also consume sergeant major damselfish eggs.

[9] Midnight parrotfish typically do not exhibit schooling behavior, as they are able to feed on algae without the assist of other organisms.

Midnight parrotfish have been seen to school with up to 30 other individuals in order to secure food from damselfish nests.

Both blue tang and parrotfish compete with damselfish for algae, and the co-schooling behavior allows both species to gain access to damselfish-protected algal clumps.