The butterflyfish are a group of brightly colored tropical marine fish that belong to the family Chaetodontidae. This group includes species such as the bannerfish and coralfish. Butterflyfish have a similar appearance to smaller versions of angelfish (Pomacanthidae), but unlike angelfish, they do not have preopercle spines at the gill covers. Some members of the genus Heniochus resemble the Moorish idol (Zanclus cornutus) of the monotypic Zanclidae. However, among the paraphyletic Perciformes, the butterflyfish are probably not too distantly related to angelfish, whereas the Zanclidae seem less closely related.