Titan Triggerfish – Facts and Photographs

Titan Triggerfish (Balistoides viridescens) is also known as the Giant Triggerfish or Moustache Triggerfish.

The Titan Triggerfish (Balistoides viridescens) is also known as the Giant Triggerfish or Moustache 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. The spine is used for defensive purposes because when raised it makes it difficult for a larger predator to swallow them. The spine is also used to lock the fish into crevices or small spaces making it difficult for predators to extract them. Triggerfish are adept at sliding into small thin crevices and their dorsal spines are then erected to lock them into place.


The Titan 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 with strong large teeth gives it a very powerful bite.

The body is an overall brownish colour crossed by browny orange lines creating a diamond shaped pattern across the body. Above the mouth there is a dark brown patch and another dark brown mark runs up the middle of the face to the eyes and then down to the pectoral fins. The area below the mouth is a whitish color.

The eyes are protruding and have a white ring around them with thin brown lines on it.  The caudal area is a whitish colour and the caudal fin is a light yellow with a brown bar at the front and rear. The dorsal fins are a yellow orange with a brown edge.  Adults can grow up to 75 cm in length and the World Record for a line caught specimen is 5.3 kg. This specimen was 53.46 cm in length so a full grown specimen would weigh more and the record in the Philippines is 7.5 kg .

Titan Triggerfish (Balistoides viridescens) is also known as the Giant Triggerfish or Moustache Triggerfish.


The Titan Triggerfish is usually seen on reefs and rubble area from 18 meters downwards and occasionally on walls.  They are adept at sliding sideways into crevices.  Usually they are seen solitary and research in Okinawa on similar species indicated that a male would have a territory overlapping that of three females.  Being highly territorial they will chase an intruder out of their territory.

Interestingly on the Tanzanian mainland which is heavily fished and was dynamited until the end of 2017, they are remarkably shy and one usually is lucky to see them disappearing off into the distance. However on Mafia Island in the Marine Park, they are habituated to divers and one can approach them very closely.


However when the female is guarding eggs the shyness disappears and I have had a female buzz me by swimming directly at my face a few times and several of my friends have been attacked. When this occurs common sense dictates one should horizontally reverse away from them as they can deliver a painful bite. One specimen bit the thick side off of a friends fin rendering it useless.  The territory of the females around her eggs  is supposedly cone shaped extending upwards and outwards from the bottom. Sometimes they just seem to ignore this cone and attack anyway.

If one is attacked the best strategy is to go onto ones back and keeping ones fins between the fish and ones self, to fin horizontally backwards and away from the nest. One should not swim upwards, but rather slightly downwards if possible to get out of the cone.  Usually once the female sees you are leaving they back off.

Titan Triggerfish (Balistoides viridescens) is also known as the Giant Triggerfish or Moustache Triggerfish.


Titan Triggerfish are found across the Indo west Pacific area from South Africa to Southern Japan, and the southern Great Barrier Reef across into the Pacific Islands.

Balistoides viridescens 3


Titan Triggerfish have a varied diet and feed on mollusks, corals, sea urchins, crustaceans and tube worms. They are caught in some areas by fishermen using a relatively small hook baited with a whole prawn or other crustacean and additionally will take lures or flies.  Their large teeth and powerful mouth are used to crush their prey.

Balistoides viridescens 2


Breeding with 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. While the female is guarding the eggs their behavior can be very aggressive.

Balistoides viridescens 1


Although they are beautiful fish, they are not commonly kept in aquariums because of their size and territorial behavior. Beyond any question of a doubt they are not reef safe and great care has to be taken with their tank mates as they will likely attack most smaller fishes. They are really not suitable for home aquariums. Because of their sharp teeth and propensity to bite great care should be taken with these fish and if the stories are correct several aquarists have been bitten by them.


Triggerfish are supposedly very good eating and are targeted by fishermen in some areas. This is unfortunate as they play a great role in keeping sea urchin populations in check.


Phylum: Chordata
Class: Actinopterygii
Order: Tetraodontiformes
Family: Balistidae
Genus: Balistoides
Species:B. viridescens


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



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