Acanthicus is a genus of large armoured catfish in family Loricariidae, native to the Amazon and Orinoco basins across Brazil, Peru, Colombia, and Venezuela. The 2 species in the atlas are among the biggest plecos in the entire family, spanning 21–39.5 in, with heavily armoured bony plates studded with prominent odontodes - small tooth-like spines - that give the body a rasp-like, spiny texture, especially pronounced along the flanks and fins of juveniles and subadults.
Both species are known to serious pleco keepers rather than the casual hobbyist, given the tank size their eventual bulk demands: the Adonis pleco (Acanthicus adonis), prized for its bold pale-spotted pattern, and the lyre-tail pleco (A. hystrix), named for its elongated caudal fin extensions, both start small in the trade but can outgrow all but the largest home aquaria and are more commonly kept long-term in ponds or public displays. Both species carry a Least Concern IUCN status.