Leporacanthicus species have large teeth in the upper jaw; usually there are only two teeth on each premaxilla, the inner teeth very long. Species of Leporacanthicus are medium-sized loricariids with a narrow, pointed head, round lower lip, and fleshy tentacles on the upper lip. The colour pattern is generally dark gray to black with white to golden spots or a light gray with medium-sized black spots. The abdomen is naked (scaleless and unplated). The caudal fin is straight and angled posteroventrally. L. galaxias are basic black with many white spots. L. triactis are brown, gray, or charcoal black, save for vivid orange or yellow blotches on the spines of the non-paired fins.
It has been hypothesized that the enlarged teeth of the upper jaw are used to remove snails from their shells. This has been observed in L. joselimai, but specimens from Venezuela seem to have a lot of caddis flies as well as freshwater sponges in the gut.