Blue-jaw Triggerfish Breeding Guide

Xanthichthys auromarginatus is a planktivorous triggerfish with strong sexual dimorphism that spawns in pairs over sand. It is not bred in home aquaria, only documented in the wild.

Overview

The blue-jaw, bluechin or gilded triggerfish (Xanthichthys auromarginatus) is an Indo-Pacific triggerfish ranging from East Africa to Hawaii, usually at depths of 20-50 m (recorded between 8 and 161 m) and reaching roughly 10-30 cm. It is planktivorous rather than benthic. Home breeding is not established; the following describes documented wild reproduction. It is typically found toward the deeper end of its range and is rarer above 20 m, and it is the second-smallest species in its genus.

Sexing

This species is strongly sexually dimorphic. Males show a blue cheek patch on the underside of the head and yellow-bordered white second dorsal, anal and caudal fins, whereas females lack these and instead have brown-margined fins.

Conditioning

No home conditioning protocol is documented. The natural diet consists almost exclusively of zooplankton, primarily calanoid copepods, so the species is a mid-water planktivore rather than a substrate digger.

Spawning Behaviour & Trigger

Reproduction is oviparous and occurs as single male-female pairs. The preferred spawning site is sandy substrate on reefs, with spawning usually taking place in the early morning. A female releases roughly 55,500 to 430,000 eggs per spawning event.

Egg & Fry Care

The eggs attach to the sand and hatch on the evening of the same day. Both parental and biparental care occur within triggerfish; after hatching the larvae enter open water, which is the stage that has prevented hobbyist rearing.

Common Challenges

Even though this is among the more reef-tolerant triggerfish and lays demersal eggs, it is not bred in home aquaria. The large adult size, paired territorial spawning and open-water larval phase make captive reproduction impractical for hobbyists.