Care Level: Moderate

Temperament: Peaceful

Reef Compatible: No

General Description: The Mertensii Butterflyfish, also referred to as the Orangetail Butterflyfish, is native to the reefs of the Indo-Pacific with exceptional specimens coming from Fiji – our first choice here at Aquatics Unlimited! Very similar in appearance to the Pearlscale Butterflyfish (Chaetodon xanthurus), except that the orange-red area at the posterior end of this species is much larger and wider. In the Pearlscale Butterflyfish, this area is small and crescent shaped. The Mertensii butterfly brings a unique presence into the home aquarium with its interesting behavior, body shape and chevron patterning. Like many butterflyfish, the Mertensii butterfly is not a good reef inhabitant because its wild diet includes various stony corals. The Mertensii butterfly may help to eradicate nuisance Aiptasia anemones. An adult Mertensii butterfly can reach a size of approximately 6″.

Diet Requirements: Mertensii butterflies are carnivores. Encouraging a butterfly to accept prepared foods can be a challenge at first. We have found that offering live brine shrimp at the beginning can gain the interest of particularily fussy or stubborn individuals. Note: All of our butterflies for sale are eating a combination of live brine shrimp and frozen foods. A diet consisting of various frozen meaty preparations such as brine shrimp, spirulina brine shrimp, mysis shrimp, and other mixed foods that include coral or sponge will maintain optimal health, immune function and coloration. Offer sheet algae to graze on, though not all individuals may show interest. We highly encourage soaking frozen foods in vitamin and fatty acid supplements, as butterflyfish have high metabolisms. It is not uncommon for butterflyfish to revert back to ignoring food altogether, or only accepting live foods, for a period of time due to the stress of a new environment.

Care Requirements: An established, minimum 90 gallon aquarium is ideal. The Mertensii butterfly will appreciate some live rock and crevices to swim through and take refuge. Butterflyfish are sensitive to nitrite and ammonia spikes, and an established tank will also offer more abundant microfauna to forage on. Given their more timid nature, a Mertensii butterfly should not be kept with overly aggressive species, especially those that can outcompete it in food resources. Compatability with other butterfly species is variable. A Mertensii butterfly would make a great addition to a peaceful fish only with live rock aquarium. Recommended water conditions, 72-78° F, KH 8-12, pH 8.1-8.4, salinity 1.020-1.025.

Purchase Size: Small: 1-1/2″ to 2-1/4″; Medium: 2-1/4″ to 3-1/2″; Large: 3-1/2″ to 4-1/2″; XLarge: 4-1/2″ or larger.

Note: Your item may not look identical to the image provided due to variation within species. Purchase size is approximate.