Acanthicus is a genus of large, South American suckermouth armored catfishes native to the Amazon and Orinoco basins, and possibly in Guyana.

[5][6] These species are found in large rivers,[3] primarily in areas with a rocky bottom and a moderate or strong current.

[2][3] Unlike A. hystrix, juvenile A. adonis shows white spots; these are reduced with age and large adults may lack them.

Their massive adult size and territorially aggressive behavior means that a very large tank is required.

[6][7][8] The territorial behavior is mostly aimed at other suckermouth armored catfishes and during disputes Acanthicus have even been known to kill Pterygoplichthys gibbiceps (itself typically considered a robust species).