Doctorfish

Doctorfish, Acanthurus chirurgus

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

The Doctorfish have oval-shaped deeply compressed bodies that have 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. They have one continuous dorsal fin with a long base that has 9 spines and 22 or 23 rays. Their body is covered with small scales.

The Doctorfish are a subtropical species found on coral reefs, over sandy bottoms, and in seagrass beds at depths up to 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 length of 39 cm (15 inches) and weigh up to 5.0 kg (11 pounds), but are more common at a length of 25 cm (10 inches) to 30 cm (12 inches). 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 nine 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 widely distributed being found both in the Eastern and Western Atlantic Ocean, however, in Mexican waters, they are found only around the Yucatán Peninsula and within waters of the eastern Gulf of Mexico.

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

The Doctorfish are accessible via hook and line and caught off the bottom in 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 Cigua Toxin. They are used extensively in the aquarium trade being small in stature and displaying interesting colorations. Caution: The spines found at their tail base provide these fish with a unique defense mechanism rendering them “dangerous” to handle as these spines can inflict major slashing wounds.

Doctorfish, Acanthurus chirurgus. Fish caught from coastal waters off Key West, Florida, August 2014, Length: 26 cm (10 inches). Photo courtesy of Dean Kimberly, Atlanta, GA. 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 photo courtesy of Dean Kimberly, Atlanta, GA.

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

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

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