FishCommonVisible while snorkeling

Orange-lined triggerfish

Balistapus undulatus

Undulating orange stripes flow across its dark green body – the reef's elegant little bulldozer, which cracks open even sea urchins.

Photo: iNaturalist – (c) zsispeo, some rights reserved (CC BY-NC-SA)

The orange-lined triggerfish (Balistapus undulatus) is one of the most colourful members of the triggerfish family: wavy orange lines run diagonally across its dark green-brown body, and its tail is a glowing orange. The undulatus in its scientific name refers to exactly this rippling pattern. In adult males the stripes around the snout disappear, leaving the face plain dark green – that is how you tell them from the females.

As decorative as it is, it is a tough customer: with its strong, chisel-like teeth it cracks open practically everything that lives on the reef. Its menu includes coral branches, crabs, snails, bryozoans and sea urchins – it picks the urchins up by their spines and keeps flipping and dropping them until it can reach the unprotected underside. With this indiscriminate appetite it is one of the reef's important "caretakers", keeping the urchin population in check and nutrients on the move.

On Hurghada's reefs it is a common sight, hammering away at the coral head-down while wrasses hover around it, snatching morsels from the rising debris. It is territorial but peaceful towards divers – unlike the notorious titan triggerfish it does not attack, at most it swims off. You can watch it well while snorkeling in the shallow coral gardens too.

Did you know?

It defeats sea urchins like a chess puzzle: it lifts them by the spines and releases them in open water – by the time the urchin lands, it often settles vulnerable side up, and the triggerfish strikes instantly.

Where can you meet it?

It occurs in almost every Hurghada coral garden: on the reefs of the Giftun Islands, the Gota Abu Ramada plateau and the El Fanadir coral wall you will regularly even hear its hammering.

Frequently asked questions

No – the hero of those stories is the much larger titan triggerfish, which can get pushy when guarding its nest. The orange-lined triggerfish is far smaller and more peaceful – it typically ignores divers as long as you watch from a respectful distance.

Look for the dark green oval body with wavy orange stripes and a bright orange tail. Its motion is distinctive too: it propels itself not with its tail but with undulating dorsal and anal fins, as if rowing while hovering.

Because it really is crunching: its strong teeth crack coral branches, snail shells and urchin tests, and water carries the sound beautifully. If you hear cracking and snapping on a dive, look around – chances are a triggerfish or parrotfish is at work nearby.