Chaetodon mertensii

Mertenss butterflyfish | Atoll Butterflyfish | Merten's Butterflyfish
Chaetodon mertensii
Chaetodon mertensii, adult, Lord Howe Is, Australia, Photo: Andrew Green
Chaetodon mertensii
Chaetodon mertensii, juvenile, NSW, Australia, Photo: Ian Shaw
Chaetodon mertensii
Chaetodon mertensii, adult, NSW, Australia, Photo: Ian Shaw
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Chaetodon mertensii
Chaetodon mertensii
Chaetodon mertensii


Temperate Australasia, Tropical Indo-Pacific


Black chevron markings on white, with yellow-orange rear body, white tail base and black band through eye. C. xanthurus in SE Asia has netted pattern on sides.


Max Size: 13 cm

Sea Temperature Range: 19.1-29.5°C

Depth: 10-120m

Habitat Generalization Index: 25.69

Also referred to as the SGI (Species Generalisation Index), this describes the habitat niche breadth of the species. Species with values less than 15 are found in a relatively narrow range of reef habitat types (specialists), while those over 25 may be found on most hard substrates within their range (generalists). Learn more here.

Conservation and Rarity

IUCN Status: Least Concern

Occurrence: Common (21.9% of sites)

Occurrence describes how often the species is found on surveys within its distribution. It is calculated as the % of reef sites surveyed by RLS divers across all the ecoregions in which the species has been observed

Abundance: Few (2 per transect)

Abundance is calculated as the average number of individuals recorded per RLS transect, where present.