Halfmoon triggerfish, Sufflamen chrysopterum

Halfmoon Triggerfish – Facts and Photographs

Halfmoon triggerfish, Sufflamen chrysopterum

The Halfmoon triggerfish, Sufflamen chrysopterum is also known as the Flagtail Triggerfish , Blue throated Triggerfish and Eye-stripe Triggerfish. Triggerfish obtain their name from the locking mechanism used to hold the dorsal spine in place. The main dorsal spine is kept erect by a second spine which locks the dorsal spine in place. Only when this trigger spine is moved can the main spine be lowered.

Triggerfish are adept at sliding into small thin crevices and their dorsal spines are then erected to lock them into place. This prevents predators from pulling them out. With their raised dorsal spine it is also more difficult for a predator to bite or swallow them.

Halfmoon triggerfish, Sufflamen chrysopterum


The Halfmoon Triggerfish has a typical Triggerfish shape, with its eyes set high on the body and far back from the mouth. This protects the eyes when dealing with urchins and some crustaceans. The skin is thick and leather like, also for protection from spiny and spikey prey.  The relatively small mouth gives it a powerful bite.

Halfmoon triggerfish, Sufflamen chrysopterum

The juveniles as seen above are a dark brown color with a yellow and white tail very similar to that of the adults. The adult upper body is a light brown color which darkens into an almost black color, the forward lower belly and underside of the mouth are a royal blue color. Below the eye there is a curved vertical yellow line extending downwards.  The lips of the adult Halfmoon Triggerfish are a light blue color. They grow up to 30 cm in length.

Halfmoon triggerfish, Sufflamen chrysopterum


The Halfmoon Triggerfish is usually seen on the edges of the reef and occasionally on walls. They are also occasionally seen feeding on the reef its self.  They seem to prefer areas with small slit like crevices and are adept at sliding sideways into these crevices.  Usually they are seen solitary and research in Okinawa indicated that a male would have a territory overlapping that of three females.  They are highly territorial and will chase an intruder out of their territory.

Juvenile Halfmoon triggerfish, Sufflamen chrysopterum

Halfmoon Triggerfish are usually very shy fish and will often go into hiding at the sight of a diver. Usually they are seldom seen far from a hiding spot and can fit into really tight places. Sometimes they will sit just outside their hiding spot and watch a diver and appear to be curious.

Halfmoon triggerfish, Sufflamen chrysopterum


Halfmoon Triggerfish are found across the Indo west Pacific area from South Africa to Southern Japan, and the Lord Howe Island. They are not found in the Red Sea area and are replaced in that area by Sufflamen albicaudatus .

Halfmoon triggerfish, Sufflamen chrysopterum


Halfmoon Triggerfish feed on crabs, bivalves, gastropods, algae, echinoids, tunicates, worms, eggs, and detritus. They are caught in some areas by fishermen using a relatively small hook baited with a whole prawn.

Halfmoon triggerfish, Sufflamen chrysopterum


Breeding with Halfmoon Triggerfish  takes place between one male and a single female. The females lay their eggs on the substrate and they are fertilized by the male. The eggs are then guarded by the female to prevent them from being eaten by predators. Research in Okinawa revealed that one male would have a territory overlapping that of 3 females.

Sufflamen chrysopterum 3


They are not commonly kept in aquariums because of their size and territorial behavior. They are however reportedly intelligent and curious fish that are very easy to feed.

Sufflamen chrysopterum 2


Triggerfish are reportedly very good eating and are targeted by fishermen in some areas.

Sufflamen chrysopterum 1


Phylum: Chordata
Class: Actinopterygii
Order: Tetraodontiformes
Family: Balistidae
Genus: Sufflamen
Species:S. chrysopterum


The Reef Guide fishes, corals, nudibranchs & other invertebrates: East and South Coasts of Southern Africa by Dennis King & Valda Fraser





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