Phycocharax rasbora Ohara, Mirande & Lima 2017

Phycocharax rasbora is distinguished by the combination of the following non-unique characters: single row of relatively compressed premaxillary teeth present; large teeth on premaxillary and dentary with four to nine cusps; pseudotympanum lacking; incomplete lateral line with 7-13 pored scales; anal fin dimorphic, males with distal margin approximately straight, anddecreasing gently posteriorly, while females present slightly concave margin of anal fin with anteriormost branched rays distinctly longer than remaining rays; horizontally-elongated somewhat triangular blotch present, extending from vertical through dorsal-fin terminus to caudal peduncle end (Ref. 116744).

Dorsal soft rays (total): 1011; Vertebrae: 32 - 34

Collected mainly in dammed portions of the rio Braço Norte where it can be considered highly abundant. Appears to be uncommon in the lotic stretch of rio Braço Norte downstream of the dam, where only three specimens were collected. At the type locality (the igarapé do Arnaldo, a small tributary which was flooded during the damming of river), this species was the most abundant comprising 77% of all specimens collected. Found syntopic at Braço Norte reservoir with other species of Characiformes such as Cyphocharax cf. spilurus (Curimatidae), Leporinus friderici (Anostomidae), Serrapinus aff. micropterus, Astyanax aff. bimaculatus (Characidae), Hoplerythrinus unitaeniatus (Erythrinidae), Gymnotiformes like Gymnotus diamantinensis (Gymnotidae), and Cichliformes, i.e., Aequidens sp. and Apistogramma sp. (Cichlidae). Co-occurs with the following Characiformes: Leporinus desmotes (Anostomidae), Hemiodus quadrimaculatus (Hemiodontidae), Astyanax aff. bimaculatus , Bryconops sp., Jupiaba polylepis , Jupiaba paranatinga , Moenkhausia hasemani , Serrapinnus aff. micropterus (Characidae); and with a single species of Siluriformes, Hypostomus sp. (Loricariidae). Males and females have well-developed gonads during rainy and dry seasons. Oocytes in varied sizes were present in the gonads, suggesting multiple spawning of females. Feeds on algae and vegetal matter (Ref. 116744).

Phycocharax rasbora is a small species of freshwater fish in the family Characidae and the only member in the genus Phycocharax. It is endemic to the Brazilian Amazon, where only known from the upper Braço Norte River (Serra do Cachimbo region), a blackwater tributary in the Teles Pires basin, itself a part of the Tapajós basin. A dam has been built on the Braço Norte River and while the species is uncommon downstream, it is very abundant in the reservoir above. Its species name refers to the similarity in color and pattern to Trigonostigma rasboras, an unrelated but well-known Asian fish. The mainly reddish males reach up to about 3.4 cm (1.3 in) in standard length, while the duller yellowish females reach up to about 3.1 cm (1.2 in).