Blue Triggerfish

Blue Triggerfish

The Blue Triggerfish (Odonus niger), better known as the redtooth triggerfish, is a striking, deep blue-green fish whose colour shifts with mood and lighting, set off by a lyre-shaped tail and — on close inspection — a set of red teeth. Hardy, graceful in the water and relatively even-tempered for a trigger, it is one of the most popular large fish for marine aquariums, swimming with an elegant, undulating motion quite unlike its blockier relatives.

It is among the more peaceable triggerfish, but it is still a big, powerful animal that needs space and robust tankmates.

Natural Habitat & Origin

Odonus niger is widespread across the Indo-Pacific, where it gathers in large aggregations on current-swept outer reef slopes and channels, feeding on plankton drifting past. It shelters in holes and crevices in the reef, wedging itself in with its dorsal trigger spine when threatened.

In the aquarium it wants strong water movement, open swimming space and substantial rockwork with caves large enough to retreat into.

Care Requirements

Maintain stable marine conditions: salinity around 1.024–1.026, pH 8.1–8.4, and a temperature of about 24–26°C (75–79°F), with strong flow. It is a large, active fish — reaching up to about 50 cm (20 inches) — and needs a big tank, on the order of 570 litres (around 150 US gallons) or more, with secure rockwork it cannot easily topple. It is hardy and undemanding once established.

Diet & Feeding

The Blue Triggerfish is primarily a planktivore in the wild, making it less destructive than triggers that crush hard-shelled prey. Offer a varied diet of meaty marine foods — frozen mysis and krill, chopped seafood and quality pellets — with some marine algae content. Feed once or twice a day; it is a hearty, reliable feeder.

Behavior & Temperament

This is one of the milder triggerfish, generally peaceful when young, though it can become territorial and more assertive as it matures, so it is best treated as semi-aggressive. Keep it with robust tankmates and provide enough space and rockwork to reduce conflict. It rearranges loose rock and substrate far less than many triggers, but is still strong enough to move things around.

Tank Mates

Suitable companions are other large, robust marine fish — tangs, large wrasses, angelfish, other moderately aggressive species — that can hold their own. Avoid small, timid fish. It is not fully reef-safe: while it largely ignores corals, it may nip ornamental shrimp, crabs and other small mobile invertebrates, so it is best in fish-only or fish-only-with-live-rock systems.

Breeding

Odonus niger is a pelagic spawner and is not bred in the home aquarium; trade specimens are wild-collected.

Common Health Issues

The Blue Triggerfish is hardy but, like all marine fish, can be affected by marine ich (Cryptocaryon irritans) and marine velvet (Amyloodinium ocellatum), particularly when stressed. Quarantine new arrivals, keep water quality stable, and provide strong flow and secure rockwork. Given the space it needs and a varied meaty diet, it is one of the easiest and most elegant large triggers for an intermediate marine keeper.