Genicanthus is a genus of marine angelfishes in the family Pomacanthidae. Known commonly as swallowtail or lyretail angelfish, these fishes are so-named for the distinctive shape of their tailfins. This genus of angels, in comparison to the other species found in hobby aquaria, are a good choice for beginners as they do not get nearly as large as some of the others. Another unique attribute is that swallowtail Angels will tolerate each other and can be kept in pairs or as a single male with a harem, though it is typically best to add them to a tank at the same time. If added on by one, the angel which is added first may become aggressively territorial towards any new additions. Unlike others in the Pomocanthidae family, the angelfish in the Genicanthus species are generally considered to be reef safe. Also unlike most other members in the Pomacanthidae family, the Genicanthus genus are sexually dimorphic, meaning males and females are easily distinguishable. Fish in this species possess a small mouth relative to its size. This small mouth is well adapted for feeding on plankton in the water column. As planktavores, members of the genus Genicanthus generally will not nip corals and sessile invertebrates.
- Ornate angelfish, Genicanthus bellus Randall, 1975.
- Zebra angelfish, Genicanthus caudovittatus (Günther, 1860).
- Blackstriped angelfish, Lamarck's angelfish, Genicanthus lamarcki (Lacépède, 1802).
- Spotbreast angelfish, Genicanthus melanospilos (Bleeker, 1857).
- Masked angelfish, Genicanthus personatus Randall, 1975.
- Halfbanded angelfish, Genicanthus semicinctus (Waite, 1900).
- Japanese swallow, Genicanthus semifasciatus (Kamohara, 1934).
- Pitcairn angelfish, Genicanthus spinus Randall, 1975.
- Genicanthus takeuchii Pyle, 1997.
- Blackedged angelfish, Genicanthus watanabei (Yasuda & Tominaga, 1970).