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 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.
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.
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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