Peixes da planície de inundação do alto rio Paraná e áreas adjacentes: revised, annotated and updated Author Ota, Renata Rúbia Author Deprá, Gabriel de Carvalho Author Graça, Weferson Júnio da Author Pavanelli, Carla Simone text Neotropical Ichthyology 2018 2018-06-11 16 2 1 111 journal article 10.1590/1982-0224-20170094 f68fe85c-2a4c-4625-b684-74f61398d6c2 1982-0224 3678395 Serrapinus calliurus (Boulenger, 1900) Fig. 10 Body elongated; greatest body depth contained 2.5 to 2.8 and caudal peduncle depth 6.7 to 8.8 times in SL; head length 3.1 to 3.6, predorsal distance 1.8 to 1.9 and caudal peduncle length 7.3 to 9.3 in SL; snout length 4.2 to 5.1, horizontal orbital diameter 2.5 to 3.0 and least interorbital width 2.8 to 3.6 in HL. Mouth terminal; premaxilla with 4-6, dentary with 6-8, and maxilla with 1 or 2 teeth. Lateral line incomplete, with 5-7 pored scales; longitudinal series with 32 or 33 scales; transverse series above lateral line with 5-6 scale rows and below with 4 or 4 ½ scale rows. Dorsal fin with 11, pectoral fin with 10 or 11, pelvic fin with 8, anal fin with 22-25 and caudal fin with 19 rays. Ground color pale yellow; dark-brown longitudinal stripe on flank, from pseudotympanum to caudal peduncle; black rounded blotch on posterior portion of caudal peduncle and caudal-fin base, extending to median caudal-fin rays. Maximum standard length. 22.7 mm . Biological data. Feeds on benthic organisms, detritus, unicellular and filamentous algae ( Fiori et al. , 2016 ). Presents absolute average fecundity estimated in 406 oocytes, and relative fecundity in 0.6 oocytes per mg ( Gelain et al ., 1999 ). Distribution. Río de la Plata basin and Laguna dos Patos drainage. Remarks. Some specimens of Serrapinnus calliurus were identified as Serrapinnus sp. 1 by Graça, Pavanelli (2007) . Both species occur in the upper rio Paraná floodplain, where S. calliurus has been captured since 2009 by the Nupélia staff. Serrapinnus calliurus can be distinguished by having dentary teeth wide, with 7-9 cusps gradually decreasing in size, and the black blotch on caudal peduncle reaching the base of median caudal fin rays ( vs. dentary teeth slender, with 3-5 cusps of different size and central cusp longer than lateral ones, and the black blotch on caudal peduncle with no extension, in Serrapinnus sp. 1). Serrapinnus calliurus is a non-native species from the upper rio Paraná and its occurence can be associated with the functioning of the Canal da Piracema (a fish ladder that connects the region downstream from the Itaipu Dam to the region upstream from the dam), or with the aquarium trade.