Doctorfish, Acanthurus chirurgus

Doctorfish, Acanthurus chirurgus, Juvenile. Underwater photograph taken with coastal waters off Cozumel Island, Quintana Roo, March 2021. Photograph and identification courtesy of Marina Sutormina, Stockholm, Sweden.

Doctorfish, Acanthurus chirurgus. Fish caught from coastal waters off Key West, Florida, August 2014, Length: 26 cm (10 inches). Photograph courtesy of Dean Kimberly, Atlanta, Georgia. Identification courtesy of Dr. Ross Robertson, Smithsonian Institute, Panama.

Doctorfish, Acanthurus chirurgus. Fish caught from coastal waters off Key West, Florida, June 2015, Length: 28 cm (11 inches). Catch and photograph courtesy of Dean Kimberly, Atlanta, Georgia.

Doctorfish, Acanthurus chirurgus. Fish caught from coastal waters off Key West, Florida, April 2017, Length: 28 cm (11 inches). Catch and photograph courtesy of Dean Kimberly, Atlanta, Georgia.

Doctorfish, Acanthurus chirurgus. Fish caught from coastal waters off Key Largo, Florida, December 2013. Length: 28 cm (11 inches). Catch, photograph and identification courtesy of Ben Cantrell, Peoria, Illinois.

Doctorfish, Acanthurus chirurgus. Fish caught from coastal waters off Big Pine Key, Florida, December 2013. Length: 26 cm (10 inches). Catch, photograph and identification courtesy of Ben Cantrell, Peoria, Illinois.

The Doctorfish, Acanthurus chirurgus, is a member of the Surgeonfish or Acanthuridae Family, and is known in Mexico as cirujano rayado and barbero rayado. Globally, there are forty-two species in the genus Acanthurus, of which seven are found in Mexican waters, three in the Atlantic and four in the Pacific Ocean.

The Doctorfish has an oval-shaped deeply compressed body that has a depth that is 48% to 52% of standard length. They vary significantly in color and can change quickly from blue-gray to dark brown to blend in with their environment. They have 10 to 12 dark thin vertical bars on their sides, which are often faint. The edges of their anal, caudal, and dorsal fins are blue and their scalpel area is dark with an encircling blue ring. The tips of their caudal fin are blunt, a key to identification. Their eyes are located high on their head. They have small mouths that are set low on the head that are equipped with teeth that are spatula-like set close together and notched on the edges, suitable for scrapping algae off rocks. They are named for the sharp “scalpel” located at the base of their tail, which is used for defense. Their anal fin has 3 rays and 22 or 23 spines; their dorsal fin has 9 spines and 22 or 23 rays and is continuous with a long base; their pectoral fins have 16 or 17 rays; and, their pelvic fins have 1 spine and 5 rays. Their body is covered with small scales.

The Doctorfish is a subtropical species found on coral reefs, over sandy bottoms, and in seagrass beds at depths up to 40 m (130 feet). They are a schooling species known to forage in groups of five or more individuals and travel with the Ocean Surgeon, Acanthurus tractus. They reach a maximum of 39 cm (15 inches) in length and 5.0 kg (11 lbs 0 oz) in weight, but are more common at a length of 25 cm (10 inches) to 30 cm (12 inches). As of January 1, 2023, the International Game Fish Association world record stood at 0.57 kg (1 lbs 4 oz) with the fish caught in coastal waters off Marathon, Florida in December 2007. Spawning occurs in pairs or in large groups of up to 20,000 individuals between December and March. Eggs hatch within 24 hours and they become sexually mature in 9 months. They are primarily diurnal herbivores that feed on filamentous and fleshy algae, detritus, and associated microinvertebrates. Food is swallowed whole and broken up by sand particles found in their intestine. They are preyed upon by large fish including barracuda, groupers, snappers, and tuna. The Doctorfish is poorly studied with very limited information available about their lifestyle and behavioral patterns including specific details on age, growth, longevity, movement patterns, diet, habitat use, and reproduction.

The Doctorfish is a resident of all Mexican waters of the Atlantic Ocean including the Gulf of Mexico and the east coast of the Yucatán Peninsula in the Caribbean.

The Doctorfish is a straightforward identification that is fairly easy to identify as it is the only Surgeonfish with bars on its sides.

From a conservation perspective the Doctorfish is currently considered to be of Least Concern with stable, widely distributed populations. They are accessible via hook and line and caught off the bottom in 8 m (25-foot) water utilizing small hooks tipped with cut squid. They are finicky nibblers with very small mouths and are thus difficult to hook. They are not considered a significant food fish, however, they are retained by subsistence fishermen catching them primarily with traps, nets, and spears. Their meat is marketed in some local markets on a limited basis. They are known to contain ciguatoxin. They are used extensively in the aquarium trade being small in stature and displaying interesting colorations.

A word of caution. The spines at the tail base of this fish provide a unique defense mechanism and can inflict major slashing wounds, rendering them dangerous to handle.