A new species – Knodus pasco sp. n. – from surroundings of San Antonio de Cacazú in Peru (Departamento Pasco) is described (Teleostei: Characiformes: Characidae). It is a small species of the genus Knodus EIGENMANN, 1911 (lateral line complete, basis of caudal fin scaled, four teeth in the second row of premaxillary bone), which differs from all congeners through the following combination of features: (1) six (rarely fi ve) maxillary teeth, (2) six (rarely fi ve) tri- to quincuspid premaxillary teeth in the outer row, which is very irregular, (3) 37–39 scales in lateral line, (4) 7/1/4 scales before dorsal fin, (5) anal fin with iv–v, 17–19, i fin rays, (6) head relatively small (3.79–4.05 times in SL), (7) a dark longitudinal band (two to two and a half scales wide) from gill-cover to the tips of middle caudal fin rays, (8) a very faint vertical humeral spot and (9) a black longitudinal band in dorsal fin.