Barberfish, Johnrandallia nigrirostris
The Barberfish, Johnrandallia nigrirostris, whose common Spanish name is mariposa barbero, is a member of the Butterflyfish or Chaetodontidae Family, known collectively as peces mariposa in Mexico. The Butterflyfish are reef fish and some of the most colorful tropical fish in the ocean. Globally, 93 species of Butterflyfish are known, however, only four of these live in the Sea of Cortez. There is only one species in the genus Johnrandallia, the species described herein, found in Mexican waters of the Pacific.
The Barberfish have a strongly compressed oval disc with a depth that is 66% to 70% of standard length. They are overall yellow in color with a whitish head and black bands on their snout, across their eyes and forehead, and along the base of their dorsal fin. They also have black areas around their eyes, on the edge of their gill cover, and on the base of their pectoral fins. Their head has a short pointed snout with a small terminal mouth that is equipped with long and slender teeth. Their anal fin has a rounded rear margin with three spines and 18 to 20 rays with the second spine being longer than the third; their caudal fin is straight; and their dorsal fin has a rounded rear margin with 12 spines, the fourth of which is the longest after which the spine length gradually decreases, and 24 or 25 rays. Their lateral line is complete and their body is covered with large rough scales.
The Barberfish are found in small to very large schools within reefs at depths up to 130 feet. They reach a maximum length of 20.0 cm (7.9 inches). They are grazers and pickers and consume small organisms including algae, gastropods, and small crustaceans. Their mode of feeding predisposes them to be cleaners, which pick parasites from other fish such as the Pacific Creolefish, Paranthias colonus.
In Mexican waters the Barberfish are found in all waters of the Pacific with the exception of Guerrero Negro northward along the central and northwest coasts of the Baja.
The Barberfish is most likely confused with the Scythe Butterflyfish, Prognathodes falcifer (inverted black “V” upper body) and the Threebanded Butterflyfish, Chaetodon humeralis (two wide vertical black bars originating from anterior and posterior first dorsal fin).
The Barberfish are sold commercially for the aquarium trade and are also of interest to divers. From a conservation perspective they are currently considered of Least Concern, being common with a wide distribution and stable populations.
Barberfish, Johnrandallia nigrirostris. Fish provided by the commercial fishermen of the greater Los Cabos area, Baja California Sur, December 2011. Length: 6.2 cm (2.4 inches).
Barberfish, Johnrandallia nigrirostris. Underwater photo taken in coastal waters off Buena Vista, Baja California Sur, June 2017. Length: 9.1 cm (3.6 inches). Photo courtesy of Bob Hillis, Ivins, UT.