Doctorfish range in length from 18 to 39 centimeters. The oval body of this species has 10 to 12 dark body bars running along their bodies that can range from bluish gray to much darker. The pectoral fin is dark on the leading edge. Individuals may change color by either lightening or darkening their coloration. Like all surgeonfish, doctorfish have a sharp "scalpel" on the base of their tail.

Doctorfish have a subtropical distribution ( 22 - 25°C; 37°N - 7°S; 89°W - 34°W). In the Western Atlantic they range from Massachusetts (USA), Bermuda, and the northern Gulf of Mexico to São Paulo, Brazil. In the Eastern Atlantic they are found in Senegal. Doctorfish live on coral reefs at depths ranging from two to 25 meters

Doctorfish are diurnal herbivores who feed on filamentous and fleshy algae using specialized spatula-shaped teeth. They also consume micro-invertebrates with the algae. They incidentally ingest a moderate quantity of inorganic material which can make up 40% of their stomach volume. Doctorfish pick up algae with their specialized teeth and swallow the algae whole. They have a gizzard-like organ in the intestine that is partially filled with sand particles to grind up food so it can be digested.