The beautiful Moorish idol is in a class by itself. Literally. This distinctively marked fish is the only species in its scientific classification, Zanclus cornutus. Since most fish families have multiple members, this is unusual. But what really sets this fish apart from others is that to many, the Moorish idol is the quintessential reef fish. It's the fish most folks readily recognize and hope to see when they go snorkeling or diving.
The Moorish idol sports a color pattern of alternating black and pale gold bars against a white background on its oval-shaped body. It has a black tail and an elongated white dorsal fin. The dorsal fin streams out behind it like a delicately waving banner as the fish gracefully maneuvers around the reef in search of food. An orange "saddle" marks its elongated snout. Adults have a bony projection in front of each eye. In males the projection is more prominent.
The Moorish idol's Hawaiian name, kihikihi, has multiple connotations: "curves," "corners," "zig-zag," and "angular," all of which seem to fit either the motions or general design of this fish.
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Maui Ocean Center photo
Like butterflyfishes, the Moorish idol is omnivorous. It prefers sponges as a menu choice and uses its elongated snout to poke into reef crevices and extract tasty morsels. Occasionally, it will snack on algae.
Moorish idols have much in common with surgeonfishes, to whom they are closely related. Teeth, scales and swimming style - using mostly pectoral fins - are similar. However, they lack the sharp scalpel located on the tail that is common to surgeonfishes. The shapes, behavior and feeding preferences of Moorish idols more closely parallel butterflyfishes than they do surgeonfishes. Like butterflyfishes, idols often are seen in pairs and sometimes swim in schools of three or four or more.
The coloring of the Moorish idol is believed to confuse predators. Bars of color that break up a fish's body outline are known as "disruptive coloration." Predators find it difficult to tell where such a fish begins and ends and even in which direction it may be traveling. The Moorish idol's eyes seem to blend in with its markings, as well. The idol's long streamer may be another natural deterrent to predation as it makes the fish appear to be a bigger mouthful than it actually is.
Like butterflyfishes, the Moorish idol is omnivorous. It prefers sponges as a menu choice and uses its elongated snout to poke into reef crevices and extract tasty morsels. Occasionally, it will snack on algae.
Not much information is available on the idol's reproductive habits. Pre-juveniles are known to be pelagic. At some point, they develop "stout, curved, pre-orbital spines," as they have been described, on each side of their heads. This stage of a Moorish idol's life cycle once was believed to be indicative of an entirely different species. The spines are shed as the juveniles develop into a more recognizable form.
Moorish idols make poor additions to a home aquarium. Aggressive in captivity, they are very picky eaters and difficult to maintain. Often, they do not survive. They need lots of space and the companionship of other Moorish idols. In the wild, growing naturally, they can attain a size of 8 inches or so.
Despite their distinctiveness, Moorish idols are sometimes confused with another species entirely: the pennant butterflyfish. To the casual observer, each can be mistaken for the other. The long white pennant of the pennant butterfly does resemble the trailing filament of the Moorish idol - but they are easy to tell apart once you know what to look for. Both species have a similar color pattern. But the pennant butterflyfish lacks orange markings on its jaw or snout, and its tail is yellow, not black.
Pennant butterflyfishes prefer to school in numbers near drop-offs but high in the water column where their preferred meal of plankton can be found. Moorish idols often forage in rocky shallows and can be found in and around reefs to depths of 600 feet. Taking careful note of a specimen's habitat and physical differences soon will enable any fish enthusiast to be able to tell the two species apart at a glance.
Pennant butterflyfishes do better than Moorish idols in home aquariums. They are peaceful and much easier to keep, earning them the moniker, "the poor man's Moorish idol." Pennant butterflyfishes sometimes are called pennants or bannerfish.
The classy Moorish idol earned its scientific name as a member of the Zanclidae family because of its long dorsal fin. The Greek word "zanclon" means sickle or scythe. They can be found throughout the Indo-Pacific and tropical eastern Pacific, and also from East Africa to the tropical Pacific coasts of the Americas.
Wherever they are found, their beauty and grace are renowned.
* Pam Daoust is an author and volunteer marine naturalist at Maui Ocean Center. "Ka Mo'olelo Moana," or "The Ocean Story," is a monthly column submitted by the Maui Ocean Center, which is open from 9 a.m. to 5 p.m. daily in Maalaea. For more information, call 270-7000.
