Johnrandallia nigrirostris, the blacknosed butterflyfish or barberfish (from the Spanish names, El Barbero or Mariposa Barbero, "the barber" or "butterfly barber"), is a species of fish in the family Chaetodontidae, the butterfly fishes. It is found in the East Pacific, and it sometimes acts as a cleaner fish. It is the only member of the genus Johnrandallia, named after the ichthyologist John E. Randall, but in the past it was commonly placed in Chaetodon.