moorish idol

moorish idol

Moorish Idol (Zanclus Cornutus): Fish Species Profile

moorish idol
Moorish Idol (Zanclus cornutus) swimming over reef, blue background. The type of fish known as Gill in Finding Nemo.

The Moorish idol fish is a beautiful creature that lives in the waters off the coast of Africa. This species of fish is known for being one of the largest goldfish in existence. The male Moorish idol fish can grow up to 10 inches long while females can reach about 8 inches. These fish are found in tropical regions near coral reefs where there is plenty of food.

In the wild, Moorish idol fish live in groups called schools. In captivity, however, they usually prefer to live alone. If kept in small tanks, they become aggressive towards each other. A large tank with many Moorish idol fish is recommended.


The name “moorish idol” derives from the Arabic word mawroshid (“beautiful”), referring to the appearance of the species. This is in contrast to the common names “butterflyfish”, “banded sea dragon“, “sea dragon”, “longnose butterflyfish”, “dragonet”, “dragon”, “daddy longlegs” and “black banded sea dragon”.

Moorish idols are found throughout the tropical waters of the Indo-Pacific region, including the Red Sea, Persian Gulf, Arabian Sea, Indian Ocean, East China Sea, South China Sea, Java Sea, Australia, New Zealand, Madagascar, Seychelles, Maldives, Sri Lanka, Thailand, Indonesia, Malaysia, Singapore, Philippines, Papua New Guinea, Solomon Islands, Vanuatu, Fiji, Samoa, Tonga, Kiribati, Tuvalu, Marshall Islands, Palau, Micronesia, Hawaii, Guam, Yap, Caroline Islands, Cocos Island, Christmas Island, Great Barrier Reef, Coral Sea, Cook Islands, French Polynesia, Tokelau, Pitcairn Islands, Easter Island, Chatham Islands, Lord Howe Island, Norfolk Island, New Caledonia, Loyalty Islands, Marquesas Islands, Nauru, Phoenix Islands, Society Islands, Wallis & Futuna, American Samoa, Northern Marianas, Midway Atoll, Johnston Atoll, Wake Island, Line Islands, Gilbert Islands, Samoa, Tahiti, Tongatapu, Rarotonga, Rapa Nui, Easter Island, Pitcairn Islands and Oceania. They inhabit depths ranging from near shore to 700 metres (2,300 ft).

The species is ovoviviparous, meaning eggs hatch inside female fish rather than externally. Females produce about 20–30 young per year, each measuring approximately 0.5 cm (0.20 in) in length. The larvae develop into juvenile fish within five months. Adults live up to 15 years.


The family Zanclidae includes over 150 species of small marine fish that are found throughout the world’s oceans. They range in size from 2 inches to 20 pounds. These fish live at depths ranging from near the surface down to 200 feet. Most zanclids feed on plankton, although some eat detritus, worms, crustaceans, mollusks, and even jellyfish. Some zanclids are known to prey on sharks.

Zanclid fishes have been recorded in every ocean basin except Antarctica, including the Arctic Ocean. They are found in both warm and cold water environments. Many species are pelagic, living in open waters. Others prefer coastal habitats. A few species are benthic, preferring muddy bottoms.

A few species of zanclids have been kept in aquariums. One of the most popular zanclids is the clown triggerfish. Clown triggerfishes are often kept in groups of up to 50 individuals. They swim together in schools and are very active during the day. At night, however, the clown triggerfish becomes quite inactive. In fact, it spends much of its time sleeping.

Origin and Distribution

The Moorish Idol is one of the most common reef fishes in tropical waters around the world. Its distribution ranges from the Indian Ocean and the Red Sea, east across the Indo-Pacific region to Australia, north to the Hawaiian Islands, and south into the Caribbean.2

While it is commonly seen in shallow water habitats such as lagoons and bays, it is also known to occur in deeper offshore waters up to 300 m deep.3 In some places, it can be abundant enough to form large schools.4

In the northeast Atlantic, the species occurs along the coast of Morocco, Spain, Portugal, France, Ireland, Scotland, England, and Norway.5

In the Mediterranean, it is common off the coasts of Greece, Italy, Malta and Cyprus.6

In the central and southwestern Pacific, it occurs in Indonesia, Papua New Guinea, the Philippines, Taiwan, Hong Kong, China, Japan, Korea, Malaysia, Thailand, Singapore, Vietnam, Cambodia, India, Sri Lanka, Myanmar, Bangladesh, Pakistan, Nepal, Maldives, Mauritius, Seychelles, Madagascar, Réunion, Comoros, Mayotte, Cocos Keeling Islands, Christmas Island, and French Polynesia.7

In the northwestern Pacific, it is found from the Ryukyu Archipelago to the Bonin Islands, Okinawa, and the East China Sea.8

In the southeastern Pacific, the species is widespread in Chile, Argentina, Uruguay, Brazil, Paraguay, Ecuador, Colombia, Venezuela, Trinidad & Tobago, Suriname, Guyana, French Guiana, Mexico, Costa Rica, Panama, Nicaragua, Honduras, El Salvador, Guatemala, Belize, and the Yucatan Peninsula.9

Colors and Markings

Moorish idols are found in tropical waters around the world, including the Caribbean Sea, the Gulf of Mexico, the Red Sea, the Indian Ocean, the Pacific Ocean, and the Atlantic Ocean. They range in size from about 5 inches up to 18 inches. Their diet consists primarily of crustaceans such as shrimp, crabs, prawns, and crayfish.

The moorish idol is one of several species of butterflyfish. Like most members of the family Chaetodontidae, it has very large eyes and a wide head. One distinguishing feature is that it lacks barbels—small fleshy appendages that help filter food particles out of water. Instead, it has a pair of long, thin, tube-like snout structures called ceratobranchial ducts. These tubes extend into the gills and collect oxygenated blood. Moorish idols have a number of different colors and markings, including stripes running along the sides of the body and a dark spot on each side of the caudal peduncle.

Moorish Idol Diet and Feeding

The Moorish Idol is an unusual type of cichlid fish. They tend to be large and aggressive, and many people find them intimidating. But there is much more to this fish than meets the eye. These are some interesting facts about the Moorish Idol.

First off, they are very hardy. Most species of cichlids prefer live food, such as flakes, pellets, and worms, although they will eat frozen or canned foods too. However, the Moorish Idol is different. This particular cichlid prefers dry foods like sand and gravel. In fact, they don’t even seem to mind being kept in water without any form of filtration.

They are quite territorial. Usually, male Moorish Idols will fight each other over territory. Females, however, are less likely to get involved in territorial disputes. Instead, females usually lay eggs and let the males take care of raising the young.

This particular species is known to breed quickly. Their breeding season lasts only a few days. During those short days, the female lays up to 300 eggs. She will guard her nest against predators while she waits for the eggs to hatch. Once hatched, the fry will remain in the nest together until they reach maturity.

These fish are omnivores. Although they will eat small invertebrates, they also enjoy eating plants. When they’re hungry enough, they’ll eat almost anything including plant material.

If you want to feed your Moorish Idol, look for a variety of foods that are easy to handle. You might start out offering a mixture of flake food, sand, and gravel. As they grow older, they will begin to accept a diet consisting solely of sand and gravel.

Tank Size and Environment

The tank size required to keep Moorish idols varies widely depending upon whether you want to raise adults or young fry. Adults are generally kept in tanks around 200 gallons in volume. These are usually very large tanks, because Moorish idols grow quite rapidly, reaching maturity within about six months.

Fry, however, must be raised in smaller tanks. When raising fry, it is essential to provide adequate light levels throughout the day. This requires providing ample space for the natural growth of plants and algae. Fry do not eat during the larval stage, so there is no need to feed them. However, once they reach the juvenile stage, they start eating, and will continue to eat until they mature into adults.

When raising fry, it is best to use an open system rather than closed systems. Open systems allow water circulation, while closed systems restrict water flow. Closed systems tend to promote algae growth, and often require additional filtration.

Disease and Health

The Moorish Idol, a species of surgeonfish native to the Indian Ocean, is prone to diseases such as Ichthyophthirius multifiliis (Ich). This parasitic protozoa causes severe infections in corals and fishes, and it is responsible for mass mortalities in captive populations. These outbreaks are typically associated with high levels of ammonia and nitrite in the aquarium environment.

In addition to being a carrier of Ich, the Moorish idol is also susceptible to bacterial skin infections, including Pseudomonas aeruginosa and Vibrio spp.

Prevention is the best means of preventing protozoan issues. Select obviously clean specimens to begin with, and carefully acclimatize them with quarantine or dips prior to placing them into the main display. Copper therapies have proven quite effective against many protists, and you are encouraged to try quinine based therapies for Cryptocaryons, Amyloodinia and other protist parasites, if the case presents.

Torn or broken fin membranes, along with blotchy coloration, can often be attributed to poor water quality. Poor water quality can lead to increased ammonia and nitrite concentrations, both of which contribute to the proliferation of bacteria and fungi.

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