Thai National Parks

Marine spacies of Thailand

Species of Thailand

Orange-lined triggerfish

Binomial name: Balistapus undulatus, Mungo Park, 1797

Balistapus undulatus, also known as the Orange-lined triggerfish is a demersal marine fish belonging to the family Balistidae, the triggerfishes. It is the only member of the monotypic genus Balistapus.


It grows up to 30 cm long. Its body has a stock appearance, oval shape and compressed laterally. The head is large and is about one third of the body length. The mouth is small and terminal and it has strong teeth.

The first dorsal fin has three spines, one of which is longer and stronger. It is erectile and kept in a dorsal furrow at rest. The second dorsal fin is similar in shape and size to the anal fin, which is symmetrically opposed to it. The pelvic fin is reduced to a ventral protrusion.

The body is dark green with orange lines. The male loses the lines on his snout as he matures. There is a black blotch on the caudal peduncle, and the caudal fin is orange.

Distribution & habitat

It is widely distributed throughout the tropical and subtropical waters of the Indian Ocean and the western Pacific. It inhabits coral reefs, lagoons and external reef slopes at depths up to 50 meters.


The orange-lined triggerfish has a varied diet based on different benthic organisms such as algae, molluscs, sponges, hard coral tips, echinoderms, and fish.


This triggerfish is diurnal, solitary, and territorial. It can be aggressive with other fish. It erects its first dorsal spine to intimidate opponents and predators.

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Scientific classification

Balistapus undulatus

Conservation status

Not Evaluated (IUCN3.1)

Not Evaluated (IUCN3.1)

Range Map

Range map of Balistapus undulatus in Thailand