Callichthys callichthys (Linnaeus, 1758)

Fig. 19

Body elongated; greatest depth contained 4.5 to 5.0 and caudal peduncle depth 6.5 to 6.7 times in SL; head length 4.3 to 4.5, predorsal distance 2.6 to 2.7 and maxillary-barbel length 3.9 to 4.1 in SL; snout length 2.2 to 2.4, horizontal orbital diameter 9.4 to 10.1 and least interorbital width 1.4 to 1.6 in HL. Mouth terminal. Lateral line with 4 pores on upper series of plates. Dorsolateral series with 26-29 and ventrolateral series with 24-27 plates. Dorsal fin with I,7 or 8, pectoral with I,6, pelvic and anal fins with 6 rays. Ground color pale brown to dark-grey. Dark-grey fins with black spots (Graça, Pavanelli, 2007).

Maximum standard length. 150.0 mm (Graça, Pavanelli, 2007).

Distribution. Widespread in South America rivers.