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Chaetodon mertensii Atoll butterflyfish

Chaetodon mertensiiis commonly referred to as Atoll butterflyfish. Difficulty in the aquarium: Only for advanced aquarists. A aquarium size of at least 1000 Liter is recommended. Toxicity: Toxic hazard unknown.

Profilbild Urheber Scott & Jeanette Johnson, Kwajalein Unterwater

Copyright Scott & Jeannette Johnson, Kwajalein Underwater, Foto Marshall Islands, Kwajalein Atoll

Courtesy of the author Scott & Jeanette Johnson, Kwajalein Unterwater Please visit for more information.

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Chaetodon mertensii 
Atoll Butterflyfish, Atoll Butterflyfish, Merten's Butterflyfish, Merten's Coralfish, Orangebar Butterflyfish 
Atoll Butterflyfish 
Family tree:
Animalia (Kingdom) > Chordata (Phylum) > Actinopterygii (Class) > Perciformes (Order) > Chaetodontidae (Family) > Chaetodon (Genus) > mertensii (Species) 
Initial determination:
Cuvier, 1831 
American Samoa, Austral Islands, Australia, Chile, Cook Islands, Easter Island (Rapa Nui), Fiji, French Polynesia, Gambier Islands, Great Barrier Reef, Guam, Indonesia, Japan, Line Islands, Lord Howe Island, Marschall Islands, Micronesia, Moorea, New Caledonia, New Guinea, Niue, Norfolk Island, Northern Mariana Islands, Ogasawara Islands, Palau, Papua, Papua New Guinea, Philippines, Pitcairn Islands, Queensland (Australia), Rangiroa, Rapa, Samoa, Solomon Islands, Sri Lanka, Tahiti, Taiwan, The Ryukyu Islands, the Society Islands, Tokelau, Tonga, Tuamoto Islands, United States Minor Outlying Islands, Vanuatu, Vietnam, Wallis and Futuna 
Sea depth:
10 - 120 Meter 
4.33" - 4.72" (11cm - 12cm) 
75.2 °F - 82.4 °F (24°C - 28°C) 
Brine Shrimps, Clam meat, Coral polyps = corallivorous, Flakes, Frozen Food (large sort), Mysis, Nori-Algae, Zooplankton 
219.98 gal (~ 1000L) 
Only for advanced aquarists 
Not available as offspring 
Toxic hazard unknown 
Not evaluated 
Red List:
Least concern (LC)  
Related species at
Catalog of Life:
More related species
in this lexicon:
Last edit:
2018-07-15 17:55:17 


Cuvier, 1831

Chaetodon mertensi is a very close relative to C. xanthurus und C. paucifasciatus. All members of this group have a similar painting. C. mertensi is the only one with a grey trapezoid shading. This shy fish is seldomly sold. In a tank with vegetable food good to keep.

Chaetodon dixoni Regan, 1904
Chaetodon mertensi Cuvier, 1831

Classification: Biota > Animalia (Kingdom) > Chordata (Phylum) > Vertebrata (Subphylum) > Gnathostomata (Superclass) > Pisces (Superclass) > Actinopteri (Class) > Perciformes (Order) > Percoidei (Suborder) > Chaetodontidae (Family) > Chaetodon (Genus) > Chaetodon mertensii (Species)

External links

  1. FishBase (multi). Abgerufen am 19.08.2020.
  2. IUCN Red List of Threatened Species (multi). Abgerufen am 19.08.2020.



Copyright Scott & Jeannette Johnson, Kwajalein Underwater, Foto Marshall Islands, Kwajalein Atoll
Chaetodon mertensii
Copyright Prof. Dr. Robert A. Patzner

Husbandry know-how of owners

am 19.12.08#3
Chaetodon mertensii, also known as Merten's Butterflyfish is widely distributed through the Indo-West Pacific, from Ryukyu Islands, south to the Philippines, Lord Howe Island, Tuamoto and Marshall Islands and found too around Easter Island.

Merten's Butterflyfish is easily recognised by its distinctive colouration. It is white with 6-7 black chevron-shaped markings on the body. The posterior portion of the body and dorsal, anal and caudal fins are yellow-orange. There is a black, silver-edged bar through them eye and a dark mark on the nape.

In the Sea, this fish is a feeder upon live coral polyps from hard stony corals, assorted benthic invertbrates, filamentous algae and possibly macroalgae too. Consequently this fish is NOT REEF SAFE in an aquarium in which live corals are being cultivated, and is unlikely to be safe with Zoanthids and certain other sessile invertebrates too! Can be migrated to more practical aquarium foods, but this may prove challenging.


Butterflyfish are not recommended for reefs as they will pick at or eat a wide variety of corals, fan worms, and other invertebrates. Most Butterflyfish are known to pick at Aiptaisia, a parasitic anemone.


Class: Actinopterygii
Order: Perciformes
Family: Chaetodontidae
Genus: Chaetodon
Species: Chaetodon mertensii

am 25.01.06#2
A peaceful fish that adapts well to aquarium life. Will eat most pod and meaty preparations with some vegetables. It is very shy when first obtained, and easily paniced. As always with most butterflyfishes, it is best to put into quarantine in order to get it eating different foods, and to get it used to humans (as well as to be sure it is disease-free). This is especially important for this fish.
am 01.06.05#1
Indo-w.Pacific; 12 cm; not so common
Formerly two species, Indian Ocean form (*) was called C.madagaskariensis with a defined black spot on head, but now it is nominal; the Pacific form with obscure marking on head (photo) is rare in Japan, but common in Australia; easily kept
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