Moorish Idol - in Aquaria

In Aquaria

Moorish idols are notoriously difficult to maintain in captivity. They require large tanks, often exceeding 100 US gallons (380 l; 83 imp gal), are voracious eaters, and can become destructive.
Some aquarists prefer to keep substitute species that look very similar to the Moorish Idol. These substitutes are all butterflyfishes of the genus Heniochus, and include the pennant coralfish, H. acuminatus; threeband pennantfish, H. chrysostomus; and the false moorish idol, H. diphreutes.