FishOccasionalVisible while snorkeling

Chevron butterflyfish

Chaetodon trifascialis

The reef's fussiest gourmet: the chevron butterflyfish eats almost nothing but table-coral polyps and defends its own coral patch for life.

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

The chevron butterflyfish (Chaetodon trifascialis) wears thin, dark, angled lines across a pearly white body – like a herringbone pattern drawn by hand. Adults have a black tail with a narrow yellow rim, while juveniles carry a large yellow-and-black tail patch, so the two life stages can look like different species at first glance. At 15–18 cm it is average-sized for a butterflyfish, but its lifestyle is anything but average.

This is one of the most specialised fish on the reef: it feeds almost exclusively on the polyps and mucus of Acropora table and staghorn corals. Each fish (or pair) claims a single table-coral colony and defends it obsessively, chasing off intruders far larger than itself. That makes the chevron butterflyfish a living health indicator – wherever you see one, the Acropora corals are doing well, because without them this fish simply cannot survive.

Around Hurghada, look for it on shallow reef tops rich in table corals, between 1 and 15 metres – exactly where we snorkel. It does not roam: once you have found its coral colony, it will still be there at the end of your dive. Approach slowly; inside its territory it is surprisingly bold and will posture at you as if you were the trespasser.

Did you know?

It is so tied to Acropora corals that the IUCN lists it as Near Threatened: when a coral colony bleaches and dies, this fish vanishes from the area within weeks – which is why researchers use it as a living gauge of reef health.

Where can you meet it?

Your best chances are on the table-coral-rich reef tops of the Giftun Islands and Gota Abu Ramada, but it also turns up while snorkeling in the shallow coral garden of Shaab Sabina.

Frequently asked questions

Yes – in fact the chevron butterflyfish lives among table corals on shallow reef tops at 1–15 metres, so snorkelers often get a better view than deep divers. The trick is to find healthy table corals – the fish will be right there.

Because that coral is both its home and its pantry: each fish owns a single Acropora colony, which it defends and grazes. Return to the same reef and you will very likely find the same individual at the same coral.

Not at all – it only chases other butterflyfish off its territory. The worst you will get is an indignant stare if you drift too close to its coral.