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Picasso triggerfish ( Rhinecanthus aculeatus ) at Bristol Zoo, Bristol, England. Photographed by Adrian Pingstone in December 2005 and released to the public domain.

Lagoon triggerfish

A small, territorial reef fish with precise swimming and maternal care.

Photo: Arpingstone, Public domain, via Wikimedia Commons

The lagoon triggerfish is a small reef dweller found across the Indo-Pacific. It uses unique fin movements for precise navigation and exhibits strong maternal care, with females guarding eggs until they hatch on the same day.

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  • Females guard eggs for 12-14 hours until hatching
  • Uses dorsal and anal fins to hover and move backwards
  • Has trichromatic vision similar to humans
  • Males maintain territories for eight years or more
  • Eggs are laid at sunrise and hatch by sunset

What it is

The lagoon triggerfish is a small member of the triggerfish family, reaching lengths of up to 30 cm. It inhabits coral reefs and sandy patches within the Indo-Pacific. The fish is known for its ability to move with great precision, using waving motions in its dorsal and anal fins to hover, move backwards, or navigate tight crevices. This maneuverability sets it apart from many other fish that swim primarily in one direction.

Where it lives

This species is distributed throughout the Indo-Pacific region. It lives specifically on coral reefs and in adjacent sandy areas. The fish prefers these shallow, structured environments where it can find shelter and food among the coral rubble and algae.

How it lives

Lagoon triggerfish are restless swimmers that feed on a wide variety of items, including invertebrates and reef algae. They are highly territorial and will vigorously defend their space against intruders, including divers. While they share a family with the much larger and more dangerous titan triggerfish, their smaller size makes them less of a threat. They have been studied for their locomotion and color vision, which appears to be trichromatic.

Breeding and life cycle

Spawning occurs in pairs around sunrise, with eggs attached to sand, rubble, or algae. The eggs hatch by sunset on the same day. Unusually for fish with external fertilization, the mother provides all parental care. She guards the clutch for 12 to 14 hours, fanning the eggs for aeration and chasing away predators like starfish. Males hold haremic territories but do not assist in egg care.

Lagoon triggerfish
A drawing made by EveryFish from what this page says. It is a diagram, not a picture of the real fish.

Fish and people

The lagoon triggerfish is not noted as a food source or aquarium trade item in the provided text. Instead, it serves as a subject for scientific research. Studies have focused on its unique swimming mechanics and its visual system, providing insights into how double cones in the eye function as independent channels for color information.

(EN) Picasso triggerfish - (FR) Baliste Picasso Rhinecanthus aculeatus juvenile, Reunion Island
(EN) Picasso triggerfish - (FR) Baliste Picasso Rhinecanthus aculeatus juvenile, Reunion Island. Photo: Francois Libert, CC BY-SA 2.0, via Wikimedia Commons
The lagoon triggerfish (Rhinecanthus aculeatus), also known as the blackbar triggerfish, the Picasso triggerfish, or the Picassofish, is a triggerfish, up to 30 cm in length, found on reefs in the Indo-Pacific region. Th
The lagoon triggerfish (Rhinecanthus aculeatus), also known as the blackbar triggerfish, the Picasso triggerfish, or the. Photo: Bernard Spragg. NZ, CC0, via Wikimedia Commons
Un baliste Picasso ( Rhinecanthus aculeatus ) en attitude d'intimidation à la Réunion .
Un baliste Picasso ( Rhinecanthus aculeatus ) en attitude d'intimidation à la Réunion .. Photo: Philippe Bourjon, CC BY-SA 3.0, via Wikimedia Commons

Questions people ask about Lagoon triggerfish

How does the lagoon triggerfish move?

It uses waving motions in its dorsal and anal fins. This allows it to hover, move forwards and backwards, and back out of crevices with high precision.

Who cares for the eggs?

The mother guards and cares for the eggs. She fans them for aeration and chases away intruders for about 12 to 14 hours until they hatch.

What is the mating system?

The species has a haremic mating system. A male territory often overlaps with one to five female territories, and males hold these areas for many years.

Good reading and sources

Where this page comes from

The facts on this page come from the Wikipedia article "Lagoon triggerfish", written by its contributors and used under the CC BY-SA 4.0 licence, and from its Wikidata record (CC0). EveryFish rewrote the text in its own words, with AI assistance, and compares every page with the article to make sure no passage is copied. It may be reused under the same CC BY-SA 4.0 licence with a link back.

It may contain mistakes, and figures change over time. Nothing here is investment or buying advice. If something is wrong, tell us. Last refreshed 2026-11-15.

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Photo credits on this page

The small pictures above come from Wikimedia Commons under free licences. Some are cropped to fit.

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