Zanclus Cornutus (Moorish Idol) Profile

Zanclus Cornutus
Moorish Idol

Last updated on August 10th, 2022 at 03:06 pm

If you’re interested in fish, chances are you’ve heard of the Zanclus Cornutus (Moorish Idol) at some point. It’s one of the most commonly found fish in the aquarium trade, and it’s known for its unique appearance and sometimes violent behavior.

But before you buy any one of these fish, there are important facts about the species that you should know, such as its physical traits, what types of conditions it needs to thrive, and how to care for it properly once you have your own specimen.

Zanclus Cornutus, or the Moorish Idol, is one of the most popular corals in the saltwater aquarium hobby. This beautiful sea creature has an array of colors, varying from bright yellow to dark brown with pink and orange spots on its body.

They are very hardy, surviving in aquariums that have low levels of dissolved oxygen and other parameters that would kill other coral fish species. They are also relatively easy to keep and breed, making them ideal for beginners looking to start their first saltwater tank or add more variety to their current setup.

Popularly known as the Moorish Idol, the Zanclus Cornutus was initially discovered in 1903 off the coast of New Zealand. This species belongs to the family Zanclidae. These small fishes are found in warmer tropical and subtropical waters across the globe, including Africa, Asia, Australia, and America.

Let’s take a closer look at Zanclus Cornutus right now!

Origin and description

Zanclus Cornutus

The Moorish idol is native to temperate marine waters. It can be found in shallow reef habitats. This species is generally solitary and territorial, except when mating or otherwise competing for food. The Moorish idol feeds on a variety of small invertebrates and also scavenges on carrion.

The most striking characteristic of Zanclus cornutus is its impressive, highly arched dorsal fin. This serves as a warning sign to predators, which are likely deterred by both its taste and venomous spines that cover most of its body. A typical fish may grow up to 18 cm (7 inches) long, but some specimens have been reported to grow over 50 cm.

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These large specimens should be treated with respect; their population has declined drastically due to over-fishing and habitat destruction. The Moorish idol is a prized aquarium specimen because of its curious nature, intelligence, and pleasing coloration which ranges from light brown to deep red.

Species profile

Zanclus Cornutus

Zanclus cornutus is a species of saltwater fish in Zanclidae family. It is also known as moorish idol or bird-fish and is commonly found in tropical and subtropical waters across the Indian Ocean, South China Sea, Western Pacific, and even the Red Sea.

The average size of Zanclus cornutus for male is 4 inches while female size can grow up to 6 inches. They have a rather short life span with an estimated age of five years old or less. They can survive at temperatures ranging from 0 to 30 degrees Celsius. At birth, they are approximately 1 cm long and weigh just 1 gram.

Preferably they feed on zooplankton such as krill, small crustaceans, etc., but it has been recorded that they have also been seen preying on larger vertebrates such as pelagic tunas and smaller marine mammals like common dolphins and whales.


Zanclus cornutus reside in warm, shallow waters of tropical coral reefs and lagoons. These fish tend to congregate around crevices of rocky and coral surfaces where there is ample food supply.

They are found on sandy bottoms near coral reefs, or near rocks not far from shore. Juveniles may be found several miles from shore. They prefer depths between 4 m and 20 m (13 ft – 65 ft). Large adults are often seen at a depth of 1 – 2 m with juveniles closer to shore.

Moorish idol size

The moorish idol is a relatively small fish, reaching about 7 inches (18 cm) to 9 inches (23 cm) in length.

Moorish idol tank size

The Zanclus cornutus can be maintained in a tank size of 100 gallons. However, to establish proper territory and reduce stress, we recommend 100+ gallon tank. A tank that is decorated with rocks and wood will add to the aquarium’s natural ambiance for your fish.

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Zanclus cornutus tank set up

Zanclus Cornutus

Moorish Idols need a lot of rockwork to feel comfortable. This is because they are territorial fish, and like a lot of places to hide in, among their rocks. They need sand too, but not as much as other gobies do.

Like most gobies, they will burrow in it and build nests out of it so be sure that you give them plenty to dig around in before you add them to your tank. Lastly, Moorish Idols need live rocks or coral rubble to provide them with a natural source of food.

You will have to take great care when choosing what kind of live rocks or coral rubble you use for these little ones. You want something that has a small amount of boring sponges and corals growing on it since these can hurt or even kill your Moorish Idol if eaten by accident.

Zanclus cornutus tank mates

The Moorish idol can be kept with a few species of fish but should not be housed with any aggressive species. Some suitable tank mates include cardinal tetras, pencilfish, silver dollars, small catfish, smaller types of gourami, or even angelfish.

Conservation Status

Near Threatened, as classified by the IUCN Red List. Much of its historic range has been heavily impacted by human activity, and it is now absent from many locations where it was previously common or abundant. Overfishing and illegal finning for use in alternative medicines have also contributed to its decline.

The combination of these factors indicates that it faces a high risk of extinction in nature in the near future.

Zanclus cornutus breeding

Zanclus cornutus is very difficult to maintain in captivity, hence, breeding may be difficult to achieve.

Are Zanclus cornutus aggressive or peaceful?

Moorish Idols are generally peaceful in nature but will resort to aggression when threatened. Most aquarists describe them as quite shy. If kept in too large of a tank, Moorish Idols may become aggressive and highly territorial towards each other. This is one of their most common habits when housed with larger, more aggressive species such as Centropyge bicolor or Ctenochaetus hawaiiensis.

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Moorish idol care

Zanclus Cornutus

Zanclus cornutus are known to grow up to 2 feet in length, while adults generally measure between 1.5 and 2 feet. Moorish idols generally weigh around 3 pounds as adults. The average lifespan of a moorish idol is around 5 years, though it has been recorded that they may live up to 10 years or more if properly cared for. Because so little is known about these fish, proper care is essential in maintaining health and wellness over their lifespan.

Moorish idol diet

Zanclus cornutus is an omnivore and will eat a variety of meaty foods, including fish and crustaceans. They also feed on algae and other plant material. Zanclus cornutus is known to take dead animal pieces directly from humans, but their diet can be supplemented with commercially prepared diets if necessary.

Water parameters

These species require stable and consistent water parameters. pH levels between 8.1 and 8.4 and salinity at 32ppt to 34ppt is recommended for these fish to live comfortably in a home aquarium setting. Ammonia, nitrite, nitrate, calcium, and alkalinity should be monitored on a regular basis with frequent partial water changes being performed to keep within those acceptable ranges which will help improve chances of survival.

Feeding can often stimulate growth; if you do not provide food items, zooxanthellae that provide nutrients from photosynthesis can deplete causing starvation. Water flow must be strong but not turbulent with tank decorations or biotopes around it to give it adequate room for expansion.

Zanclus cornutus lifespan

The Zanclus cornutus lifespan is usually up to five years if healthy. These fish have a propensity for mouth and fin rot, so it’s not uncommon for hobbyists to have to euthanize them when their quality of life is no longer satisfactory.

Parasites and diseases

Zanclus cornutus are hosts to a variety of parasitic and diseases. These include: ichthyobodo, monogeneans, Trigonoscutum coryphaenoides larvae and parasites called isopods. These parasites take up residence in marine aquariums where moorish idols live.

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The best way to avoid them is by ensuring your fish never go through long periods without food or starving. The second best way is by maintaining good water quality and carrying out regular small maintenance tasks on your tank such as performing regular water changes and cleaning filters regularly. If you do find yourself with an infestation, then act fast as they will quickly spread, if not removed immediately.


Zanclus cornutus are prey to a wide variety of predators within their habitat. These include but are not limited to Octopus, Seahorses, other fish, and even sea snakes.

Does Zanclus cornutus make good pets?

No. Zanclus cornutus species of fish isn’t suited for home aquariums because they are very territorial and will eat most other fish in an aquarium set up. If you want to keep a Moorish idol, it’s best to purchase a pair and provide them with their own tank. The tank should be furnished with lots of live rock and sheltered areas or caves that they can hide in when they aren’t eating. They do best in tanks that have good water flow and high temperatures.