Threeband butterflyfish in Los Cabos

How to recognize it

A strongly compressed, oval, disc-shaped body with a short, pointed snout and a small mouth. It is white to silvery white, sometimes with a creamy tint. Look for three black bars: one running from the throat up through the eye to the nape, a second just behind the head over the base of the pectoral fin, and a third across the rear of the body near the tail base. The dorsal, anal and tail fins carry black bands and black rear edges. The lateral line rises in a high arch and stops below the dorsal fin.

Biology

The threeband butterflyfish lives only in the eastern Pacific, from southern California and Baja through the Gulf of California to Peru and Chile, including the Cocos, Malpelo and Galápagos islands. It lives on rocky reefs from 3 to 55 m deep and is most common between 5 and 12 m, often close to shore.

It is usually seen in pairs or small groups. FishBase describes pairs as monogamous. It feeds on algae and small bottom invertebrates, and it sometimes schools with Pacific spadefish. At Cabo Pulmo it was recorded in fish counts between 1987 and 1998, but it was not among the species rated common there.

Seeing them from the boat

The threeband butterflyfish is a fish for snorkelers and divers, not anglers. Look for pairs over shallow rocky reefs around Los Cabos. It is not a sport fish.

Its mouth is small and it feeds on algae and tiny invertebrates, so it is rarely hooked. If one ever comes up, unhook it gently and put it back. Aquarium collectors need a federal fishing permit. Sport fishing is not allowed inside Cabo Pulmo National Park.

Rules & conservation

Not a sport fish. If one is ever hooked, release it.

Don't confuse it with

The barberfish (Johnrandallia nigrirostris) is yellow with a whitish head, a black snout and mask, and a black stripe along the base of the dorsal fin. The Pacific spadefish (Chaetodipterus zonatus) is silvery with six black bars, has a blunt snout and grows much larger, to 66 cm, usually over sand or rubble. The Moorish idol has a yellow rear body and a long white streamer from the dorsal fin.

Questions

By Max VargasTop Anglers, Cabo San Lucas · international judge at big game fishing world championships · reviewed October 2026

Sources

• Smithsonian Shorefishes of the Eastern Pacific: Chaetodon humeralis
• FishBase: Chaetodon humeralis
• Reef Life Survey: Chaetodon humeralis
• The ETYFish Project: Chaetodontidae
• Villarreal-Cavazos et al. 2000, fishes of Cabo Pulmo reef (Rev. Biol. Trop.)
• Gijón-Díaz et al. 2017, ornamental reef fish fishery in Mexico (Rev. Biol. Trop.)
• Smithsonian Shorefishes of the Eastern Pacific: barberfish
• Smithsonian Shorefishes of the Eastern Pacific: Pacific spadefish
• NOM-059-SEMARNAT-2010, 2019 annex (DOF)
• NOM-017-PESC-1994, 2013 amendment (DOF)
• Aburto-Oropeza et al. 2011, fish recovery at Cabo Pulmo (PLoS ONE)

Top illustration: Top Anglers. Photos: iNaturalist contributors, credited on each photo.