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Moorish Idol Care Guide

Table of Contents

  •   Common Names: Moorish Idol
  •   Scientific Names: Zanclus cornutus
  •   Size: 20 – 25 cm max.
  •   Minimum Tank Size: 400 liters (excluding filtration)
  •   Reef Safe: Relative
  •   Care or Experience Level: High – Expert Level
  •   Preferred Diet: Small polyp hard corals, small crustaceans, zooplankton, coralline algae and sponges
  •   Original Part of the World: Coasts of Africa, East Africa, Red Sea; Indian Ocean; Japan

·   Aggression Level: Low (Peaceful)

There are some star pieces of reef aquariums. This can be an invertebrate, a stunning hard coral or sometimes it can be a bright colored sand worm.

On the other hand, most of the time it happens to be a fish, which is shining, has bright and beautiful colors.

Today we will talk about a main cast; but this one is not special with having one of the above features to be a star piece of the aquarium but, it is a beautiful, yet fragile and most prestigious member of the tanks.

It is a Moorish Idol. Let’s have a close look at their life and try to discover what makes these fish this much rare and stunning.

Moorish Idol Behavior


Moorish Idols are very peaceful fish and have good relations with many other species. They love to swim in the middle section of the aquarium and through the gaps and spaces between the rocks in the daytime and search for live food on the rocks and between the corals constantly.


They also love to hide in the caves at night, to be in comfort and save while they are having their sleeping periods. They can be a bit fragile if the conditions change but, yet they are strong enough to get through for a period of time in those conditions, if they are kept in good conditions for a long time. 

But, if the conditions change in a sudden or very often, this can affect the feeding behaviors and fish can put itself in a death fasting; to avoid that from happening; keeping their environmental specialties in a standard is very important. 


They are sensitive to water conditions with also the conditions of the reef that you create for them. They need caves, curves, places to be hidden and all the conditions which a reef can serve, this also includes waves and streams through the tank. 


While you are choosing a Moorish Idol to buy for your tank; you should follow the rules you always do for every fish; bright colors, transparent fins and crystal-clear eyeballs are signs of a healthy fish. 


Also, following their behavior in the exhibition tank for 1 or 2 minutes is always helpful to pick. Always pick the one which swims freely and acts feeding behaviors in the tank. Opposite of these can be a sign of a parasite or a pathogen which can affect all your tank conditions and also the other members.


They are peaceful and good with many non-aggressive species for keeping together in the same tank. Because there have no phenotypic differences between male and female, another thing to pay attention to is keeping them alone or more than 3 Moorish Idols in the same tank, this can be good for their survival and behavior improvement.

Moorish Idol Appearance

These fish have lateral flattened body type with following stripes colored onyx black, bright white and fluorescent yellow on both sides through the tail to their mouth. Also, they have just a hint of an orange color at the back tip of the mouth, which is at the end of a long tubular snout. 


All fins are quite small except the dorsal fin. That fin has a long and narrow flag shape which is usually 10 cm to 15 cm and can be rarely 30 cm long. Sometimes dorsal, flag shaped streamer fin can be harmed or loosened. If the fish has proper caring, good environmental conditions and feeding quality; that fin will grow again in a two to three weeks period of time.

Moorish Idol Tank Conditions

  • Temperature: Between 24 – 26 degree celsius
  • Flow: Vertical and Horizontal, medium to strong flow
  • Size: 80 cm height and 80 cm wide minimum
  • Water Type: Crystal clean, well mineralized, rich with nutritions
  • Filtration: Strong and supported with bio and chemical filtration
  • Lighting: Equivalent to daylight with following daily cycle through day and night

Moorish Idol Tank Mates


  • A few good options; Member of families Acanthuridae and Grammatidae, Chromis fish, Clown fish.

  • A few bad options; Any kind of Damselfish, Puffer fish, members of family Balistidae. 

Moorish Idol Diet

Their food diet and nutrition needs are a bit different from surgeonfish; Moorish Idols do not graze. They are coral eaters, they also eat small crustaceans, zooplankton, coralline algae and sponges.


If you are planning to keep your fish in a live reef tank, that will be very good for their comfort and you will see that they will get used to their new tank very quickly. But also, you should be aware of getting rid of some of your precious corals.


Their feeding behavior on coral polyps and coralline algae can cause blech on hard corals and kill whole coral or at least a part of it. If you are planning to keep them in an artificial coral reef or fish tank; supporting their diet with small shrimp pieces, living zooplankton like brine shrimp (Artemia sp.) is very important to keep them in shape and alive.


If a Moorish Idol cannot find anything to eat in the aquarium that they like; they prefer to starve to death instead of eating dry fish food or anything you serve for the other fish in the tank. This makes them very fragile and causes stomach problems, if a Moorish Idol has a collapsed stomach, it is very hard to convince it to go back to eat and survive.


It is not always very easy to make a Moorish Idol get used to the dry food. You should follow a feeding cycle to make that happen. Every time, you should first feed the fish with dry fish pellets which have around 1 mm diameter sized pieces and contain rich high proteins then, immediately bring up the brine shrimp or shrimp pieces. 


This feeding cycle might give the chance to get the behavior and be comfortable only feeding with pellets in 1 or 2 months. 


The following suggestions can be a good choice for food; 

  • Dry brine shrimp cysts and hatching them by yourself and feeding the fish with live brine shrimp. 
  • Frozen, cleaned up shrimps, unfreeze and cut into small pieces 2-3 mm max.
  • Highly protein richen pellets 1mm sized. 


How Big Do Moorish Idols Get?

Their common size is around 10 – 12 cm and can get 20 to 25 cm length maximum in captivity.

How Do Moorish Idols Breed?

They can hardly breed, almost impossible in captivity. Because their need for breeding is pelagic; females spread their eggs to the water column and males fertilize the eggs when they are passed through them.

The fertilized eggs then join the zooplankton chain in the pelagic zones. These conditions are nearly impossible to have in artificial tanks. 


Frequently Asked Questions

Yes, it is. However, this is a very hard challenge and a long way to go with the fish. Needs high expertise and patience.

Yes, if you follow the constant feeding cycles and suitable methods.


No, they do not. It is nearly impossible.

Yes, they are peaceful but they do not live with all species. Choosing the species which has a herbivore diet is the best choice as tank mates.

Yes, they are. But they feed on hard corals and coralline algae.

Yes, they are. But it is very hard to adapt a Moorish Idol to an artificial coral reef aquarium because of their feeding behavior of live crustaceans, coralline algae and hard coral polyps.

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