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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.

Population dynamics allows comprehension on how population assures its success on continuity of the species and the balance of its population density. Thus, in order to analyze reproductive parameters (i.e., gonadal maturation stages, fecundity, and recruitment) and population aspects (i.e., length-weight frequency, asymptotic length, growth and mortality rates, and sex ratio) of Odontostilbe paraguayensis Eigenmann & Kennedy (1903) (Characiformes: Characidae) in the southern Pantanal of Brazil, samples were carried out from February 2009 to January 2011 along the main channel of the Paraguay River and its tributary, the Amonguija River, with seine net and a rectangular sieve (0.8 x 1.2 m). To estimate population parameters, the data of 604 individuals were recorded, and for reproductive aspects, the data of 394 individuals were recorded. The sex ratio was 3:1 (females:males). The estimated asymptotic length (L∞) was 36.67 mm. The population had high growth rate values (k = 1.3 year-1) and mortality (Z = 1.98). Longevity was estimated as 2.3 years. The mean absolute fecundity was 420.2 oocytes/female. Absolute fecundity was positively related to total weight (g) and gonad weight (mg). For females, the standard length at first maturity (L50) was 24.1 mm, and for males, it was 27.6 mm. Reproducing females were more frequent in March and April, although females with ripe gonads were recorded nearly all year long. The recruitment pattern was long with positive correlation with the average historic level of the Paraguay River, considering seasonal flooding. The lengthweight relationships were not different between the sexes, but they presented negative allometric growth. Thus, during ontogeny, the species presents more increment in length than in weight, and, consistent with the high growth rate, this may be understood as a way to reach longer lengths faster to avoid predation. The outcomes demonstrate that O. paraguayensis has a short life cycle with high growth and mortality rates. Together with the long recruitment pattern and high fecundity, the species may be considered an r-strategist.

Patterns of species replacement and richness differences along environmental gradients or ecoregions shed light on different ecological and evolutionary mechanisms acting on community structure. Communities of aquatic ecosystems of different watersheds are supposed to host distinct species and lineages. Quantifying and understanding the degree to which these differences are affected by environmental and biogeographical factors remains an open question for these environments, particularly in the Neotropical region. We investigated patterns of taxonomic and phylogenetic composition of headwater streams of the Paraná and Paraguai River basins to understand how local and biogeographical factors affect the assembly of fish communities. We also quantified taxonomic and phylogenetic beta diversity by decomposing them into nestedness and turnover components. We found that local environmental factors are the main factors influencing the composition of stream fish communities. Whereas pH affected both taxonomic and phylogenetic turnover, water velocity was responsible for phylogenetic turnover and pH was the main driver of phylogenetic nestedness. Our results indicate an effect of local environmental factors in determining the structure of headwater stream fish communities through a combination of a species sorting mechanism (water velocity and pH) and phylogenetic habitat filtering (pH). RESUMO Padrões de substituição de espécies ou diferenças de riqueza ao longo de gradientes ambientais ou ecoregiões lançam luz sobre diferentes processos e mecanismos ecológicos atuando na estruturação das comunidades. Supõe-se que comunidades aquáticas pertencentes a diferentes bacias pertençam a linhagens evolutivas distintas. Quantificar e entender o grau em que tais diferenças são resultado de fatores ambientais locais e/ou processos biogeográficos ainda é uma questão pouco explorada. Neste estudo nós investigamos os padrões de composição taxonômica e filogenética em riachos de cabeceira das bacias dos Rios Paraná e Paraguai, para entender como fatores locais e biogeográficos afetam a estruturação das comunidades de peixes. Nós quantificamos a diversidade beta taxonômica e filogenética decompondo estas em aninhamento e substituição. Encontramos que os fatores ambientais locais são os principais determinantes da composição das comunidades de peixes destes riachos. Enquanto o pH afetou tanto a substituição de linhagens e de espécies, a velocidade da água foi responsável por uma substituição de linhagens, enquanto o pH foi o principal responsável pelo aninhamento de linhagens. Nossos resultados indicam a importância dos fatores locais através da combinação entre mecanismos de preferência de nicho (velocidade da água e pH) e filtragem ambiental de linhagens (pH).

This paper aimed to define the reproductive period and population parameters of Serrasalmus marginatus relative to local environmental features, such as day length, rainfall and mean river level. The study site was a floodplain in the Negro river, Pantanal, Brazil, and samples were collected bimonthly using gill nets and cast nets with meshes from 1.5 to 8 cm between adjacent knots. The reproduction period, as determined by gonadosomatic index (GSI) and percentage of gonad stages, varied significantly along the year (F₄,₁₁₆ = 77.5; p

With the aim to analyze intra- and interspecific variation in the life history characteristics and recruitment pattern of six fish species, samples were conducted in two different hydrological regime areas of Pantanal (synchronous/Norther and asynchronous/Southern regions - high temperatures and rainfalls are and are not coincident with the flooding period, respectively). In both regions, fish were sampled using sieve net and dragnet along the river and marginal lakes. In the synchronous regime (Cuiaba River), the combined data collected between the years 2005 and 2010 were utilized. In the asynchronous regime (Paraguay River), the collections were made between 2009 and 2011. Length frequency data were used in the FISAT program to estimate the parameters. Four species, in the synchronous regime, reached trend to longer values for the asymptotic length values (L∞) and trend to lower values in growth taxa (k) and mortality (Z), but the outcomes did not demonstrate significant intraspecific variation for L∞ and Z by length classes between the hydrologic regimes (except for Moenkhausia dichroura). The recruitment pattern did not show intra- and interspecific variation between the hydrological regimes, with long period of recruitment and greater pulse for all species between June and August. Thus, the correlation of species recruitment with river level in the asynchronous regime follows the flood pulse concept, where the flooding pulse is the main driving force for production of animal and plant biomass. In contrast, the pattern of recruitment in the synchronous regime follows the hypothesis of the low flow recruitment, where the recruitment is not influenced by flooding, despite the period of high temperature and rainfall being coincident with the period of flooding.

Biodiversity is inherently multidimensional in nature, differences in evolutionary history, attributes of species, taxonomic composition constitutes a small fraction of whole variation present in this multidimensional space. Despite its multidimensional characteristic, biodiversity has been traditionally measured by assessing its dimensions separately through metrics of diversity. However, assessing multiple dimensions in a common framework opens the possibility of answering interesting questions that, until now, are poorly understood, such as: What dimensions capture most of the variation present in biodiversity among communities? We assess this question by extending the framework of Importance Values (IVs) to three dimensions of variation in biodiversity, functional, taxonomic and phylogenetic, and evaluate which of these captures the most variation in biodiversity space. To address this question we used data from stream fish communities of the Ivinhema River Basin in Brazil. We found that functional and phylogenetic dimensions are more important than the taxonomic dimension (represented by richness) in capturing variation in the biodiversity space formed by these three dimensions together. Furthermore, the IVs of these three dimensions were similar along an altitudinal gradient, indicating similar contributions by a given dimension in different environmental conditions. We highlight the importance of adopting a multidimensional approach when describing biodiversity, since richness (the proxy for taxonomic dimension), despite being the most commonly used, is an incomplete surrogate to capture the variation present in the biodiversity space of stream fish communities.

Astyanax lineatus was previously known only from the Paraguay river basin and we report the first record from the Paraná river basin near the municipality of Sidrolândia, Mato Grosso do Sul state, Brazil. The species was found in Lajeado Stream, a tributary of the Anhanduí River, which belongs to the Pardo River sub-basin of the Paraná river basin.

Ecological literature offers a myriad of methods for quantifying β-diversity. One such methods is determining BDtotal (BD), which, unlike other methods, can be decomposed into meaningful components that indicate how unique a community is regarding its composition (local contribution) and how unique a species is regarding its occurrence in the metacommunity (species contribution). Despite this advantage, the original formulation of the BD metric only assesses taxonomic variation and neglects other important dimensions of biodiversity. We expanded the original formulation of BD to capture variation in the functional and phylogenetic dimensions of a metacommunity by computing two new metrics — BDFun and BDPhy — as well as their respective components that represent the local and species contribution. We tested the statistical performance of these new metrics for capturing variation in functional and phylogenetic composition through simulated metacommunities and illustrated the potential use of these new metrics by analyzing β-diversity of stream fish communities. Our results demonstrated that BDPhy and BDFun have acceptable type I error and great power to detect the effect of deep evolutionary relationships and attributes mediating patterns of β-diversity. The empirical example illustrates how BDPhy and BDFun reveal complementary aspects of β-diversity relative to the original BD metric. These new metrics can be used to identify local communities that are of conservation importance because they represent unique functional, phylogenetic and taxonomic compositions. We conclude that BDPhy and BDFun are important tools for providing complementary information in the investigation of the structure of metacommunities.

In order to inventory the species richness and fish fauna composition along the Ivinhema river basin, 232 stretches of rivers and streams were sampled from 2000 to 2018, using a rectangular sieve, trawls, gillnets, cast nets, and electrofishing. A total of 141 species was caught in the basin, including seven orders and 35 families. For the recorded species, 42 are from the upper Paraná river, 51 from lower Paraná river, 27 from other basins, two from other continents, and the origin for 19 species are unknown/not reported. Six species are registred for the first time in the upper Paraná river basin: Astyanax abramis, Moenkhausia oligolepis, Serrapinnus kriegi, Curimatopsis myersi, Pyxiloricaria menezesi, and Cichlasoma dimerus. This is the first complete survey of the ichthyofauna in lotic environments along the whole Ivinhema river basin, containing relevant information for comparing studies and serving as reference data that can contribute to the management and implementation of politics for conservation of the basin. This survey also increases 24 species on the list of the most complete inventory in the upper Paraná river published in 2007.

In the period of October 2007 to August 2008, 152 specimens ofPygocentrus nattereri were caught in the Negro River in the Nhecolândia region, central Pantanal wetland, State of Mato Grosso do Sul, Brazil. The specimens were necropsied and a total of 4,212 metazoan endoparasites were recovered, belonging to 10 taxons:Procamallanus (Spirocamallanus)inopinatus, Philometridae gen. sp.,Eustrongylides sp., Brevimulticaecum sp.,Contracaecum sp. (Nematoda), Echinorhynchus paranensis (Acanthocephala), Leiperia gracile,Sebekia oxycephala, Subtriquetra sp. 1 andSubtriquetra sp. 2 (Pentastomida). This is the first record of two parasite species from P. nattereri: E. paranensis and L. gracile. No período de outubro de 2007 a agosto de 2008, 152 espécimes dePygocentrus nattereri foram capturados no rio Negro na região da Nhecolândia, parte central do Pantanal, Mato Grosso do Sul, Brasil. Os espécimes foram necropsiados e um total de 4.212 endoparasitas metazoários foram colhidos, pertencentes a 10 táxons: Procamallanus(Spirocamallanus) inopinatus, Philometridae gen. sp., Eustrongylides sp.,Brevimulticaecum sp., Contracaecum sp. (Nematoda), Echinorhynchus paranensis (Acanthocephala),Leiperia gracile, Sebekia oxycephala,Subtriquetra sp. 1 e Subtriquetra sp. 2 (Pentastomida). Este é o primeiro registro de duas espécies de parasitas emP. nattereri: E. paranensis e L. gracile.

This study defined some population parameters for growth of the Red-bellied Piranha (Pygocentrus nattereri) in the Pantanal, based on the bimonthly length-frequency distribution of individuals in samples taken from October 2005 through August 2008 in the Negro River. The samples were taken by means of gill nets and cast nets, with meshes of 1.5–8 cm between adjacent knots. The standard length of the fish ranged from 10.2 to 30.2 cm with a mean of 20.51 ± 3.39. The gonadosomatic index (GSI) varied significantly among months (F = 5.45; p

No presente trabalho foram analisados os parâmetros de crescimento, a relacao peso-comprimento e a influencia da variacao sazonal do rio Miranda, alto rio Paraguai, sobre o periodo reprodutivo de Prochilodus lineatus. As amostragens foram realizadas mensalmente entre abril/2000 e outubro/2003. A equacao que descreve a relacao peso-comprimento total para femeas foi Pt=0,01213*Ct 3,039 e para os machos Pt=0,01322*Ct 3,012 . O comprimento total assintotico estimado foi de 55,68cm e taxa de crescimento K = 0,46/ano e Rn = 0,183 foram estimados pela frequencia de classes de comprimento. O tamanho de primeira maturacao (L50) foi estimado em 28,2cm. O indice gonadossomatico (IGS) variou significativamente entre os meses (H = 136,61; p possam iniciar a atividade reprodutiva, a fim de garantir aos ovos e larvas as condicoes ambientais ideais encontradas nos meses subsequentes de cheia, fato este verificado pela alta proporcao de femeas maduras de setembro a dezembro. A expectativa de vida de 6,5 anos foi compativel com as 6 coortes estimadas pela curva de crescimento

During the study of metazoan parasites of freshwater fish in the Pantanal wetland (state of Mato Grosso do Sul, Brazil), third-stage larvae of Brevimulticaecum sp. were collected from the abdominal cavity, liver parenchyma, mesentery, skeletal muscles and stomach wall of the following species: Gymnotus inaequilabiatus, Hemisorubim platyrhynchos, Hoplias aff. malabaricus, Myleus levis, Pseudoplatystoma corruscans, Pygocentrus nattereri, Serrasalmus marginatus and Sorubim lima. The larvae exhibited the main characteristics of the genus Brevimulticaecum, such as short ventricular appendices and the position of excretory pore and excretory nucleus. This is the first report and description of larval specimens of Brevimulticaecum parasitic in these hosts, which are fish species distributed throughout South America.

Summary Length–weight relationships (LWR) were estimated for 17 species and total length at first maturity (L50) for three species of freshwater fishes from the Miranda River, southern Pantanal, Brazil. The b values were compared for some species in the Paraguay River basin with the northern (Cuiaba River) part of the basin; differences in length–weight relationships were significantly different for Pseudoplatystoma corruscans, P. reticulatum (syn. P. fasciatum). First references on L50 and LWR are presented for two and eight fish species, respectively, as well as the new maximum total length for two species.

Com o objetivo de inventariar os metazoários endoparasitos em Serrasalmus marginatus, no Rio Negro, Pantanal, Mato Grosso do Sul, Brasil, foram examinados 91 espécimes capturados no período de outubro de 2007 a agosto de 2008. Foram registrados seis táxons parasitos: Procamallanus (Spirocamallanus) inopinatus, Contracaecum sp. (Nematoda), metacercária do tipo Diplostomulum (Digenea); Brevimulticaecum sp. (Nematoda); e Sebekia oxycephala, Subtriquetra sp. 1 e Subtriquetra sp. 2 (Pentastomida). As últimas cinco espécies citadas são registradas pela primeira vez em S. marginatus. ABSTRACT - In order to inventory the metazoan endoparasites of Serrasalmus marginatus, 91 specimens were examined. They were captured in the Negro River in Pantanal wetland, State of Mato Grosso do Sul, Central-Western Brazil, from October 2007 to August 2008. Parasites of six taxa were recovered: Procamallanus (Spirocamallanus) inopinatus, Contracaecum sp. (Nematoda), metacercarial type Diplostomulum (Digenea), Brevimulticaecum sp. (Nematoda) and Sebekia oxycephala, Subtriquetra sp. 1 and Subtriquetra sp. 2 (Pentastomida). The latter five species are reported for the first time in S. marginatus.