The Moorish Idol (Zanclus cornutus) is another stunning fish that does very poorly in the home aquarium. These fish, while very similar in appearance to the Heniochus butterfly fish, are actually more related to tangs, specifically the Acanthruidae family of tangs. The Moorish Idol can be found all throughout the Indo-Pacific, in and around reef flats where it grazes on a wide variety of foods throughout the day. Additionally, these fish can get quite large, reaching almost 10″. A fish this size would require an aquarium of almost 200 gallons, and even that is pushing it in my opinion seeing as how much these fish (and other tangs for that matter) travel on a daily basis in the wild.
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The Moorish Idol is a very finicky eater, hence its poor survivability in the home aquarium. In the wild, these fish eat sponge, tunicates, benthic (bottom dwelling) invertebrates, and will graze various algae…even coralline algae. In the home aquarium, the Moorish Idol’s diet is severely limited. The live rock present in the tank may have some coralline algae and sponge or tunicate growth, but they won’t last long with something eating them. Most of the items on a Moorish Idol’s diet are fairly slow growers and an average hobbyist won’t be able to provide the proper nutrition for these fish. So, after a brief stay in your tank, the fish will starve to death.
If you have already purchased a Moorish Idol, or know someone who has, there are ways to keep them properly fed. Though most hobbyists have had terrible luck, some have been able to keep their idols alive by feeding them a huge variety of aquarium-safe foods. Additionally, some sponge and tunicate species are available to purchase, provided your local aquarium store has a wholesaler who carries them. But despite most efforts, most Moorish Idols rarely live past a year in captivity and are therefore better left in the ocean.
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