The Moorish idol (Zanclus cornutus) with its classic shape and long pointed nose was brought into public prominence by the Pixar film, Finding Nemo. Today they adorn beach towels, shower curtains, clothing and even wall paper. Along with its exotic looks and mystical name it inspires a feeling of warm relaxed tropical reefs. They are beautiful fish.
They were initially classified as a type of butterflyfish. Fossils of extinct similar species have been found and the species now has its own family and moorish idols are the only surviving member of the Zanclidae family.
The body of moorish idols is circular in shape and very narrow in width. The dorsal spines are elongated backwards into a filament which grows longer as the fish ages and trails behind it as it swims. It has a protruding tube like nose which puckers up at the end. The mouth has a yellow saddle across the top and bristle shaped teeth. The base color of the body is white with alternating bands of black and pale yellow bars. The eyes are set high up away from the mouth and on adults there are bumps above the eye.
IN THE WILD
Moorish idols are a common sight on the reefs in Tanzania and are often seen in shoals of three or four fish. At times of the year, normally during summer large shoals are often seen. They feed during the day and at night they adopt a drab coloration at night presumably for camouflage purposes. They are nervous of divers and always keep their distance. They happily swim sideways under overhangs or go into a hole sideways if they feel threatened.
Their range includes the East Coast of Africa from the Kwa Zulu Natal south coast northwards, across the Indian Ocean excluding the Persian Gulf and Red sea , across Micronesia and Australia to Hawai and the Gulf of California south to Peru.
Their long nose and mouth with bristle like teeth is adapted to picking algae, coral polyps, tunicates, sponges and benthic invertebrates off the rocks and out of crevices.
Moorish idols spawn and release eggs into the water table. The eggs then hatch and enter a larval stage which lasts for several months and probably accounts for their wide distribution. They have not been bred in captivity.
Moorish idols are extremely difficult fish to keep in an aquarium. They are finicky eaters and they stress easily. They are also not reef safe and great care has to be taken with their tank mates particularly so that there is no competition for their food source. Their personalities will also vary greatly.
Only if you are an experienced aquarist with a well established large tank with lots of overhangs and hiding places should you even think of keeping them. Even then you may want to think twice. It is best to start with young fishes that have not been stressed and their diet will need to be supplemented with lots of live rock. Some people have had success feeding them dried seaweed and vitamin enriched spirilina.
If you have a tank with high volume traffic walking past, the Moorish Idol will not settle in easily and to start with it would be sensible to keep them in a secluded tank. Initially you will have to approach the tank very carefully and slowly until they learn to associate you with food and your presence does not stress them. You may have to restrict access by others to the tank for a period of time.
To help get them to settle in an old trick is for the first month or two to always wear the same color shirt when approaching the tank and feeding them. Fish quickly learn to associate a colored shirt with food instead of stressing. If you do not believe this go to a public aquarium and see what color shirts the staff wear. Go back again with the same color shirt on and see how popular you are at most tanks.
To keep these fish successfully you need to get the basics right with lots of small tricks like this to prevent the fishes from stressing. Unless you are really confident you can get the diet and all the other factors right , do not try and keep these fish.
Cuvier in Cuvier and Valenciennes, 1831
Species: Z. cornutus
Allen, G., R. Steene, P. Humann and N. Deloach. 2003. Reef Fish Identification. Tropical Pacific. New World Publications, Inc., Jacksonville, Florida and Odyssey Publications, El Cajon, California.
Burgess, W. and H. R. Axelrod. 1973. Pacific Marine Fishes. Book 1. T. F. H. Publications, Inc., Ltd.