All fish / Chaetodontidae

Merten's butterflyfish

Chaetodon mertensii

Also known as mertens butterflyfish, merten's butterfly, atoll butterflyfish, chevron butterflyfish, mertensi butterfly, ミゾレチョウチョウウオ, kepe-kepe, 默氏蝴蝶鱼

A white butterflyfish with dark chevron markings along the flanks, a black eye bar and a bright orange rear body and tail. It is one of the hardier butterflyfish because it eats a broad diet rather than relying on coral polyps, so it suits fish-only and some reef systems.

Care at a glance

Care level

Moderate

Temperament

Peaceful

Adult size

11 cm

Temperature

24 to 27 °C

pH

8.1 to 8.4

Smallest tank

300 litres

Keep as

Singly or as a mated pair

Diet

Omnivore: mysis, chopped seafood, marine flake and pellets, algae-based foods

Swims

Middle of the tank

Lifespan

5 to 10 years

Water

Marine (saltwater)

Wild range

Western and central Pacific, from Ryukyu Islands to the Great Barrier Reef and French Polynesia

Breeding

It is a pelagic spawner that releases eggs into open water, and the larvae pass through a long planktonic stage. It has not been bred regularly in home aquariums.

Good to know

Likely to nip soft corals, anemones, tubeworms and some LPS corals, so it is not fully reef safe. It looks similar to C. xanthurus and C. madagaskariensis, which have a different tail colour or markings.