Picasso Triggerfish Breeding Guide

Rhinecanthus aculeatus is a haremic, demersal nest-spawner: females attach eggs to substrate and guard them. It is not bred in home aquaria, only documented in the wild.

Overview

The Picasso or lagoon triggerfish (Rhinecanthus aculeatus) is an Indo-Pacific reef fish reaching up to 30 cm and feeding on invertebrates and reef algae. Unlike the pelagic-spawning wrasses and angelfishes, it builds a substrate nest and guards its eggs in the wild. Home breeding is not established; the following describes documented wild reproduction.

Sexing

The mating system is haremic, with one male overlapping the territories of one to five females. Males maintain their territories for eight or more years, while females hold theirs for shorter periods. Reliable visual sexing is not described in the source.

Conditioning

No home conditioning protocol is documented. In the wild the male's long-held territory and a harem of females provide the social setting for repeated reproduction over a lifetime.

Spawning Behaviour & Trigger

Pair-spawning takes place around sunrise. The egg masses are attached to sand, coral rubble or algae, and the eggs hatch the same day around sunset.

Egg & Fry Care

Maternal care is the norm in this species, which is unusual for a fish with external fertilisation. The female guards the eggs for about 12-14 hours, fanning them with her pectoral fins roughly 30% of the time, chasing away predators and removing intruders by mouth. Experimental removal of the mother resulted in near-zero egg survival, showing how essential this guarding is. After hatching the larvae enter open water.

Common Challenges

Although this species lays and guards demersal eggs rather than broadcasting them, it is not bred in home aquaria. Its strong territoriality (intensifying during nesting), large adult size and the open-water larval phase together make captive reproduction impractical for hobbyists.