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Arapaima gigas (Schinz), the "pirarucu", is one of largest freshwater fish of the Neotropical region, naturally occurring in the Amazon, Essequibo, and Orinoco river basins. Herein, it is first recorded from the Grande River, in the upper Paraná River basin. This record is based on the finding of one dead specimen on the left margin of the Grande River, and in situ observation of juveniles and adults in the river. [ABSTRACT FROM AUTHOR]

Among Neotropical freshwater ecoregions, the Mid-Northeastern Caatinga (MNCE) is a fish knowledge gap. Its temporary drainages are receptors of the São Francisco interbasin water transfer project (SFR-IWT) in the Brazilian semiarid. We provide a comprehensive baseline of fish richness of the five SFR-IWT basins. Species richness, shared, endemic, threatened and non-native species were obtained using sampling, ichthyologic collections, literature and online repositories (306 localities). In total 121, species were recorded, 111 of them native, and 16 (14.41%) listed for all basins. Higher richness of native species (78, 70.27%) was recorded in the São Francisco lowermiddle stretch (SFRE), including 23 endemic, 61 (54.95%) in MNCE basins (13 endemic), and 28 (25.23%) shared between both ecoregions. In the MNCE, 50 species were recorded in Jaguaribe (JAG), 39 in Piranhas-Açu, 36 in Paraíba do Norte, and 32 in Apodi-Mossoró (APO). The number of species shared between the SFRE and each receptor basin varied from 24 (23.08%, JAG) to 20 (22.22%, APO). JAG contains 81.97% of the receptor basins' species. Its higher richness and endemism deserve special attention regarding the ongoing hydrological changes. This study will help detect possible modifications in the ichthyofauna of the main MNCE drainages. [ABSTRACT FROM AUTHOR]

A checklist of recent and fossil fishes of the Order Characiformes is presented herein and believed to be complete through 2022. A total of 47 collaborators checked and provided information about their taxa of expertise. The list is arranged in alphabetical order by family and then genus and includes all available synonyms. From a total of 3,087 species group names and 527 genus group names, 2,334 species are currently treated as valid, and assigned to 301 genera and 24 families. This total includes 25 species known only from the fossil record, of which 21 are assigned to eight extant families and four are Incertae sedis in Characiformes, but does not include five species based on fossil which were wrongly treated in Characiformes. The status of 79 nominal species remains unresolved. When there are two competing hypotheses about the validity of a name, one of them is chosen and the alternate interpretation is provided in the remark section of that name. Distributional summaries are presented as numbers that correspond to areas for which there is a record of occurrence of the species. A list of unavailable names is provided at the end since some of those names may need additional research to certify their status. [ABSTRACT FROM AUTHOR]

Neotropical Ichthyology promotes the Special Issue (SI) “Human impacts and the loss of Neotropical freshwater fish diversity” with the purpose of publishing relevant scientific articles on the current biodiversity crisis and the loss of Neotropical freshwater fishes in the Anthropocene. The SI is composed of 22 publications, being two review articles and 20 original articles. A total of 107 researchers contributed to these papers, involving 44 institutions based in Brazil and six other countries. Published articles investigated main anthropic activities and their impacts on fish diversity, with special focus on river regulation, mining, land use changes, aquaculture, and fisheries. Studies provided evidence about the loss of fish diversity in the Neotropics, including fish kill events, demographic changes, contamination, changes in assemblage structure, loss of taxonomic and functional diversity, besides the degradation of ecosystem functions and services, and the lack of effective protection and conservation. Studies were conducted in rivers, streams, lakes, and reservoirs from different Neotropical systems. The studies published in this SI represent a relevant sample of the current worrisome situation of freshwater fishes in the Neotropical region and call for urgent revision in environmental policies, management and conservation initiatives, and socioeconomic priorities. [ABSTRACT FROM AUTHOR]