The Neotropical region hosts 4225 freshwater fish species, ranking first among the world's most diverse regions for freshwater fishes. Our NEOTROPICAL FRESHWATER FISHES data set is the first to produce a large‐scale Neotropical freshwater fish inventory, covering the entire Neotropical region from Mexico and the Caribbean in the north to the southern limits in Argentina, Paraguay, Chile, and Uruguay. We compiled 185,787 distribution records, with unique georeferenced coordinates, for the 4225 species, represented by occurrence and abundance data. The number of species for the most numerous orders are as follows: Characiformes (1289), Siluriformes (1384), Cichliformes (354), Cyprinodontiformes (245), and Gymnotiformes (135). The most recorded species was the characid Astyanax fasciatus (4696 records). We registered 116,802 distribution records for native species, compared to 1802 distribution records for nonnative species. The main aim of the NEOTROPICAL FRESHWATER FISHES data set was to make these occurrence and abundance data accessible for international researchers to develop ecological and macroecological studies, from local to regional scales, with focal fish species, families, or orders. We anticipate that the NEOTROPICAL FRESHWATER FISHES data set will be valuable for studies on a wide range of ecological processes, such as trophic cascades, fishery pressure, the effects of habitat loss and fragmentation, and the impacts of species invasion and climate change. There are no copyright restrictions on the data, and please cite this data paper when using the data in publications.

A new species of Characidium from southeastern Brazil is described based on morphological and molecular evidence from specimens collected between the rio Jucuruçu and rio Doce basins. The new species belongs to a group of species within Characidium with an unscaled area in the isthmus and is distinguished from these species, except C. alipioi, C. fasciatum, C. hasemani, and C. kamakan, by the greater distance (greater than 10% SL) and presence of 5-7 scales between the anus and the anal fin, and presence of 14 series of scales around the caudal peduncle. The species is distinguished from C. alipioi by having 4 series of scales above the lateral line (vs. 5 series) and greater distance between the anus and the anal fin; from C. fasciatum and C. kamakan, by the smaller body depth at the dorsal-fin origin, at the anal-fin origin, and at the caudal peduncle; from C. hasemani, by the short distances between the tip of the snout and the pelvic fin, the tip of the snout and the anal fin, and the tip of the snout and the tip of anal fin. The new species forms a presumably monophyletic group with C. alipioi and C. kamakan.

Paragenidens, a new genus of ariid catfishes is proposed to accommodate Arius grandoculis, a species previously assigned to the genus Potamarius. Paragenidens grandoculis is an endemic ariid catfish categorized as Critically Endangered and probably Extinct from coastal lacustrine systems from Espírito Santo and Rio de Janeiro states, southeastern Brazil. After more than 50 years without records of the species, new recent fieldwork revealed that the species is extinct at lagoa Juparanã, but still can be found at lagoa Nova in Linhares municipality, Espírito Santo state. Here, Paragenidens is described based on morphological and molecular evidence. In addition to its generic reassignment, the species is redescribed, and comments on its phylogenetic relationships, biogeography and conservation are presented.

The occurrence of the species of the genus Brycon (Characiformes: Bryconidae) in Espírito Santo State is herein reviewed. Brycon opalinus, a species formerly known only from the upper rio Paraíba do Sul and upper rio Doce basins, is recorded for the first time in the rio Itapemirim, an independent coastal basin in southern Espírito Santo State, Brazil. With the records of B. opalinus, four Brycon species are now known from Espírito Santo State: B. insignis in the rio Itabapoana basin, on the boundary between Rio de Janeiro and Espírito Santo, B. opalinus in the rio Itapemirim basin, B. dulcis in the rio Doce basin, and B. ferox in the rio Barra Seca, rio Itaúnas and the rio São Mateus basins. Additionally worth highlighting is that several fisherman and local inhabitants report the occurrence Brycon vermelha in the rio Cotaxé, a tributary of the rio São Mateus in Espírito Santo and Minas Gerais states, although there are no preserved specimens of B. vermelha from river basins other than the rio Mucuri, in Minas Gerais state.

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