Acanthodemus Marschall, 1873 Parancistrus is a small genus of suckermouth armored catfishes native to South America.

[1] There are currently two recognized species in this genus:[3] Parancistrus is unique among loricariids due to the presence of fleshy folds on the naked area around the dorsal fin and at the pectoral fin points insertion in the breeding males.

[1] Breeding males also have elongated odontodes on their bodies and pectoral fin spines.

Their color is typically slate gray to black, occasionally with white streaks.

They have large gill openings, which makes the genus different from all other loricariids except some Pogonopoma and Rhinelepis.