The African Diving Experience

Fishwatch
 Triggerfish nr1 - 6

On this Page: Titan, Orangestriped, Clown, Indian, Redtooth, Blue

Next: Wedgetail, Boomerang, Bridle, Halfmoon, Whitetail

Then: Gilded, Striped, Outrigger, Bluelined

1) Titan or giant triggerfish, Balistoides viridescens

The Titan or giant triggerfish, Balistoides viridescens (Bloch & Schneider, 1801) is the biggest and “baddest dude” of the Balistidae.  With a maximum size of 70 cm and a thick muscular body, this heavyweight trigger can deliver a painful blow (when it rams you head-on), and its bite is even more to be feared.  Not only does the Titan vigorously defend its nest, but some divers have discovered that it will also attack and bite without provocation.  But the Titan is not all bad; as the major predator of the crown-of-thorns starfish, the Titan trigger plays a valuable role in the coral-reef ecosystem.  It is known from depths of 5-50 m and   occurs from the Red Sea to South Africa (south to Aliwal Shoal) and islands of the central Pacific Ocean.

2) Orangestriped triggerfish, Balistapus undulatus

Divers also need to keep their distance from the orangestriped triggerfish, Balistapus undulatus (Mungo Park, 1797), as it bites savagely and can also inflict wounds with the sharp spines on the caudal peduncle.  This photo shows a juvenile; the adult male lacks the orange spots or lines on the snout.  The species occurs in depths 2-50 m and is known from the Red Sea and Indo-West Pacific region, extending south on our coast to Aliwal Shoal.  Attains  23 cm.

3) Clown triggerfish, Balistoides conspicillum

As implied by its scientific name, Balistoides conspicillum (Bloch & Schneider, 1801), the clown triggerfish is easily recognised by its conspicuous colour pattern with large, round, white blotches on the lower half of the body.  Small juveniles have white spots all over the body; but unlike the adults, the juveniles are rarely seen, because of their cryptic habit of hiding in caves and crevices on the reef.  The clown trigger  It occurs in 5-60 m on coral reefs  of the Indo-West Pacific region, from South Africa (south to Aliwal Shoal) to the islands of the central Pacific Ocean.  Attains 50 cm.

Titan

Titan Triggerfish

Orangestriped

Orangestriped Triggerfish

Clown

Clown Triggerfish

4) Indian triggerfish, Melichthys indicus

Underwater, the Indian triggerfish, Melichthys indicus, Randall & Klausewitz, 1973, looks pitch black, with brilliant white lines at the base of the dorsal and anal fins and round the edge of the caudal fin.  If you get up close and the light is good,  you may be able to see the longitudinal, bluish green or yellow lines formed by series of small spots on the body.  The tail fin is truncate to slightly rounded  Occasionally observed in small groups well above the bottom apparently feeding on plankton.  It is found in depths of 5-35 m, from the Red Sea to Aliwal Shoal and across the Indian Ocean to Sumatra and western Thailand.  Attains 25 cm.  The very similar black trigger, Melichthys niger (Bloch, 1786), which also occurs in South African waters, has the rear edge of the tail fin concave or lunate, with no white edge.

Indian

Indian Triggerfish

5) Redtooth triggerfish, Odonus niger

Adult redtooth triggerfish, Odonus niger (Rüppell, 1836), have a distinctly lunate tail fin, with the upper and lower lobes greatly elongated; the protruding lower jaw gives the fish a pugnacious look, with small, reddish teeth protruding from the upper jaw.  The anterior rays of the dorsal and anal fins are elongated, forming pointed lobes.  Colour varies from purple to violet or black, often with a pale zone in the middle of the body, and the head can be dull yellowish green, with a violet band from mouth to lower end of gill opening; the median fins have a pale blue margin.  Juveniles have the rear edge of the tail fin truncate or convex, with a white margin centrally.  Odonus niger is common at Sodwana Bay where it is generally seen in loose groups feeding on zooplankton several metres above the bottom.  When chased, this triggerfish ducks into a hole on the reef, but sometimes the hole is not big enough for the fish, and a good bit of the tail is left exposed.  This resembles an ostrich with its head in the sand.  Ranges from Red Sea to Aliwal Shoal and across the Indian Ocean to the central Pacific.  Attains 30 cm (snout to base of tail fin).

6) Blue triggerfish, Pseudobalistes fuscus

This small juvenile of the blue triggerfish, Pseudobalistes fuscus, is about 5 cm long and looks very different from the larger juvenile shown on the previous page.  This fish was photographed some years ago by Dr A Wright in his aquarium in Durban.  A good example of how aquarists can help us learn more about our fishes by documenting the variation in the colour patterns of our local species.

Juvenile-Adult

Scrawled patterns in change between juvenile and Adult

Redtooth

Redtooth Triggerfish

Juvenile Blue

Juvenile Blue Triggerfish

Adult Blue

Adult Blue Triggerfish

Triggerfish Index

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Text and photos Dr Phil Heemstra

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Updated on: 23/03/2001

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