Chaetodon trichrous (Tahiti butterflyfish) is a species of fish in the family Chaetodontidae.
This species is included in the subgenus Lepidochaetodon. In 1984, André and Roland Bauchot Maugé proposed to include this species in a new genus Mesochaetodon.
Chaetodon trichrous can reach a length of about . The back half of the body is dark brown to black, while the front part is grayish, with a small vertical black stripe through the eye. The tail is yellow.
These fishes feed over hard substrate and on plankton. They usually live singly, in pairs or in small groups.
This species is endemic to French Polynesia (Marquesas Islands, Society Islands, Tahiti, Tuamotu Archipelago) in the central-south Pacific Ocean.
Chaetodon trichrous prefers shallow coastal habitats, lagoon reefs and rocky reefs, at depths between 3 and 25 meters.