The Boomerang Triggerfish (Sufflamen bursa) is also known as the Bursa Triggerfish and the Scythe 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.
The Boomerang 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.
The nose and lower belly are a light blue grey color and the main section of the body is a light brown color with pale grey lines on it. Depending on the angle one views the fish from , the main part of the body can appear light grey or light brown. The fins are a light translucent grey blue color. A white line runs along the body from the mouth onto the mid belly. Just below the eye is a curved vertical yellow stripe and there is a similar stripe just behind the gill plate. The Boomerang Triggerfish has the ability to change the color of these stripes from yellow to dark brown dependent on mood. The change is almost instantaneous. They grow up to 25 cm in length.
IN THE WILD
The Boomerang Triggerfish is seen across a wide variety of habitats, they are found from sandy flats with algal growth to rubble areas and deep walls. It is seldom that one sees them on areas of dense coral growth. They seem to prefer areas with small slit like crevices and are adept at sliding sideways into these crevices. Usually only one is seen in a given area but on one occasion we viewed one sliding into a crevice only to come flying out backwards followed by an irate larger specimen which proceeded to chase the smaller specimen off. Clearly they are highly territorial.
They are usually very shy fish and will often go into hiding at the sight of a diver. 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 but that is not common behavior. They are not that easy to photograph well.
Boomerang Triggerfish are found across the Indo west Pacific area from East Africa to Southern Japan, Hawaii and the Great Barrier Reef.
Boomerang 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.
Breeding with Triggerfish usually 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. At this time the females may become aggressive towards divers.
They are not commonly kept in aquariums because of their size and territorial behaviour.
Triggerfish are reportedly very good eating and are targeted by fishermen in some areas. They reportedly prefer whole shrimp or prawns as bait.