Redtooth Triggerfish

The Redtooth Triggerfish (Odonus niger), also called the black triggerfish, is a distinctive Indo-Pacific reef fish named for its reddish teeth, visible when the mouth is open. Unlike most triggerfish, which are solitary and territorial, it is notably gregarious, often forming large aggregations over reef drop-offs and slopes where it feeds on drifting plankton in the water column. Its uniform blue-green to purple coloring and crescent-shaped tail with trailing lobes make it easily recognizable. Found from the Red Sea and East Africa to the central Pacific, it is common and widespread, occupying an important role as a plankton feeder on outer reef slopes.

• Elongated body up to about 40 cm
• Uniform deep blue-green to purplish coloring, sometimes appearing almost black in low light
• Crescent-shaped tail fin with elongated upper and lower lobes
• Reddish teeth, visible when the mouth is open, giving the species its name
• Pale blue lines radiating around the eyes
• Erectile first dorsal spine typical of triggerfish
• Often observed as part of a large, loosely organized aggregation over reef drop-offs

Distinguished from other triggerfish by its schooling habit, uniform blue coloring, and lyre-shaped tail, rather than the bold patterning seen in most Balistidae species.

Redtooth Triggerfish occur throughout the tropical Indo-Pacific, from the Red Sea and East Africa to Japan, Australia, and the central Pacific. They favor outer reef slopes, drop-offs, and current-swept channels where plankton concentrates, typically at depths of 5-40 m. Large aggregations are commonly seen hovering above reef structure, feeding in the water column, and retreating into reef crevices for shelter when threatened or at night. Strong currents along steep outer walls bring a steady supply of drifting plankton, making these current-exposed edges the preferred long-term feeding grounds for schools of this species.

Unlike most triggerfish, Redtooth Triggerfish are highly gregarious, often forming large schools of dozens to hundreds of individuals over reef drop-offs, where they feed by picking zooplankton from the passing current. They remain near shelter and quickly dive into reef crevices when threatened by predators, wedging themselves in place using their locking dorsal spine. Despite their schooling habit, individuals can show localized territoriality around preferred shelter sites. Spawning follows a pattern typical of triggerfish, with pairs or small groups guarding a nest site on the reef. Their plankton feeding links them closely to the pelagic food web above the reef.