Johnrandallia nigrirostris also commonly referred as the Blacknosed Butterflyfish, Barberfish or Mariposa barbero has a deep compressed body, and small protractile mouth with brush-like teeth. Its body is silvery-yellow with black bands on snout, forehead, and along base of dorsal fin, and a black raccoon-like mask around his eyes.
The Berberfish is distributed from Sea of Cortez to Panama, southward to Columbia, and the Archipiélago de Colón (Galapagos) and other offshore islands along the west-coast of South-Amerika. It is often found in very large schools in rocky areas and coral reefs at depths from near the surface to 40 meters deep.
Barberfish are best known as facultative "cleaner fishes." as juveniles. They occupy sites called "cleaning stations" where other fishes go to be cleaned of crustaceans and other ectoparasites. They known to feed mainly on algae, mollusks, and crustaceans. As a sidenote, this is one of the toughest of species of its family. The habitat of the Barberfish is is rocky reefs from 3m to 25m at night. I never found them in open, sandy or other environs. The Barberfish prefers larger quarters with as much rock and coral rubble cover as you can provide.
Butterflyfish are not recommended for reefs as they will pick at or eat a wide variety of corals, fan worms, and other invertebrates. Most Butterflyfish are known to pick at Aiptaisia, a parasitic anemone.