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Pirarucu is a carnivorous fish species from the Amazon river basin. There is growing interest in pirarucu farming, but scarce information for specific diets is a limitation. We analyzed the muscle tissue amino acid profile of pirarucu in order to estimate its amino acid requirements by using a diverse sample pool. Wild pirarucu was captured in the Araguaia and Caiapós river basins (Tocantins, Brazil). Farmed pirarucu was purchased from fish farms in the states of Maranhão and Tocantins (Brazil). Fish were sampled in two size classes: 1.66 ± 0.22 and 10.49 ± 1.07 kg body weight. Multivariate statistical analyses were applied to amino acid profiles among the groups, using R software with Vegan package. Muscle amino acid profiles varied according to pirarucu origin and size class. Estimated values can be adopted to formulate diets for pirarucu. Pirarucu fillet is a good source of essential amino acids for human consumption. [ABSTRACT FROM AUTHOR]

ABSTRACT We reviewed the scientific literature to assess the current status of recreational fishing in the Neotropical region. In total, 122 publications met our criteria and are included here. Since 1990, the number of studies published on recreational fishing in the region significantly increased. Recreational fishing was evaluated in 13 countries and two territories. Most studies were in marine environments. In total, 372 fish species captured through recreational Neotropical fishing were registered. In South American countries, the presence of nonnative species was significant. Studies were concentrated in a few countries or were not published in scientific articles, conference papers, or book chapters, and some aquatic environments, such as coastal areas, bays, coastal lagoons, and reservoirs, were not studied. In addition, there are few lines of investigation into the practice of this activity in the region, and new investigations are necessary, especially with respect to environmental problems. [ABSTRACT FROM AUTHOR]

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Introduction: Understanding the various aspects of the reproductive biology of fish is a key step towards applying effective strategies for sustainable management of fishery resources. Objective: We aimed to evaluate the sex ratio, reproductive period and lengths at first maturity for 30 fish species caught in the Verde River, upper Paraná River Basin, Brazil. Methods: Fish were sampled monthly from November 2010 to March 2011 and from October 2011 to February 2012, and sampled quarterly from May to August in 2011 and 2012; totaling 14 samples. Fish were measured and weighed in the laboratory. In addition, gender and gonadal developmental stage were identified macroscopically. Subsequently, the sex ratio was determined and significant differences were tested using the chi-square ((f) method. The reproductive period was determined with the use of gonadal developmental stages and the gonadosomatic index. Lastly, length at first maturity was estimated only for the species that presented individuals with sufficient immature and mature gonads to adjust the model. Results: Of the captured individuals, 51.5 % were male, and 48.5 % were female. Fifteen species showed significant differences in their sex ratios. The reproductive period for most species occurred from October to February, with reproductive peaks in November, December and January. The length at first maturity was estimated for only five species, including Salminus brasiliensis, a keystone species. Conclusions: The sex ratios revealed that for many species, there is a predominance of males over females, which was not expected for this parameter. The reproductive period follows the same pattern observed in Neotropical fish. However, it is noteworthy that some species are starting their reproduction in August. Lastly, estimating length at first maturity for most Neotropical fish remains a challenge, which may lead to difficulties in the use of protective measures to maintain fisheries and conserve fish species. [ABSTRACT FROM AUTHOR]

Astyanax is a species-rich, non-monophyletic genus composed of several supraspecific taxa that are poorly delimited. The Astyanax fasciatus complex is one of these taxa and shows high taxonomic complexity. To elucidate the evolutionary history of the A. fasciatus complex from southern South America, we conducted cytogenetic, molecular and morphological analyses in specimens from the Uruguay River basin. Cytogenetic characters demonstrated two closely related operational taxonomic units: Astyanax sp. 1 (8 m +22 sm +10 st +6 a), Astyanax sp. 2 (8 m +24 sm +10 st +4 a) and natural hybrids (8 m +23 sm +8 st +5 a). 5S ribosomal DNA sites were found in two pairs of m chromosomes and one pair of a chromosomes in Astyanax sp. 1, two pairs of a chromosomes and one pair of m chromosomes in Astyanax sp. 2, and three m chromosomes and three a chromosomes in hybrids. As 51 sites were found in three chromosomes in Astyanax sp. 1 and in five chromosomes in Astyanax sp. 2 and hybrids. Mitochondrial sequence analyses did not separate the two units and hybrids. Morphological analyses revealed differences between Astyanax sp. 2 and hybrids. This secondary contact with gene flow between lineages that diverged long ago might slow or reverse the differentiation/speciation process. These results help us to understand the evolutionary history of this highly complex clade of Astyanax in southern South America. [ABSTRACT FROM AUTHOR]

Copyright of Biota Neotropica (Edicao em Iingles) is the property of Biota Neotropica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The freshwater fish fauna of the Neotropics comprises one of the most diverse ichthyofaunas globally. The Iguaçu ecoregion of the Neotropics includes about 100 described species, of which ≈70% are endemic and the majority of these are considered to be threatened with extinction. As is the case in freshwaters worldwide, the Iguaçu ecoregion has been strongly impacted by a variety of factors, including urbanization, agriculture, the construction of dams and the introduction of non-native species. There is, however, a paucity of information on fish invasions and their impacts in the Iguaçu ecoregion. To address this knowledge gap an exhaustive literature review was conducted to determine the extent of introductions, the main vectors of introductions and the major risks associated with the introduction of non-native fish into the Iguaçu ecoregion. A total of 41 studies concerning non-native fish in the Iguaçu ecoregion were found, the majority (56.1%) from lists of species and first records of non-native species; while 29.3% of the studies only mentioned possible negative impacts of non-native species and 14.6% of studies evaluated, indirectly, the impacts of non-native species. The Iguaçu ecoregion has a long history of fish introductions, beginning with the first record of the "common carp" Cyprinus carpio in 1944, and continuing to the recent record, in 2012, of Steindachnerina brevipinna. Since 1944, 29 non-native species have been introduced, 19 from different ecoregions of the Neotropics, and 10 introduced from other zoogeographic regions (Ctenopharyngodon idella, C. carpio, Hypophthalmichthys molitrix, H. nobilis and Misgurnus anguillicaudatus from Palearctic region; Clarias gariepinus, Oreochromis niloticus and Tilapia rendalli introduced from Ethiopian region, and Ictalurus punctatus and Micropterus salmoides from Nearctic region). The main vector of introduction was aquaculture, with the aquarium trade, baiting, sport fishing and stocking also playing roles. Studies indirectly investigating the establishment and spread of the introduced species in the Iguaçu ecoregion found nine non-native species which were considered established. Moreover, studies evaluating the impact of non-native species have investigated changes in the feeding habits of non-native species, suggesting competition with native species for food resources, and the increase in the number of fish species introduced over time. The impacts of non-native fishes, often associated with other environmental changes, such as the construction of dams and pollution in the Iguaçu ecoregion, may have severe consequences for the endemic fish fauna, resulting in the further decline and potential extinction of native species. [ABSTRACT FROM AUTHOR]

The biomonitoring of aquatic ecosystems in developing countries faces several limitations, especially related to gathering resources. The present study aimed at comparing the responses of fish and benthic macroinvertebrates to environmental change, to identify which group best indicates the differences between reference and impacted streams in southern Brazil. We determined reference and impacted sites based on physical and chemical variables of the water. For the analysis and comparison of biological responses, we calculated 22 metrics and submitted them to a discriminant analysis. We selected from this analysis only six metrics, which showed that the two studied assemblages respond differently to environmental change. A larger number of metrics were selected for macroinvertebrates than for fish in the separate analysis. The metrics selected for macroinvertebrates in the pooled analysis (i.e., fish and macroinvertebrates together) were different from those selected in the separate analysis for macroinvertebrates alone. However, the metrics selected for fish in the pooled analysis were the same selected in the separate analysis for fish alone. The macroinvertebrate assemblage was more effective for distinguishing reference from impacted sites. We suggest the use of macroinvertebrates as bioindicators of Neotropical streams, especially in situations in which time and money are short. [ABSTRACT FROM AUTHOR]

Spatial and temporal variations in food supply play a crucial role in the determination of the patterns of food use by fish species. This study evaluated spatial and temporal variations in food utilization by small fish species of the Verde River, Upper Paraná River Basin, state of Mato Grosso do Sul, Brazil. Samplings were conducted in the rainy and dry periods, from November 2010 to August 2012, using trawls, cast nets and gillnets, in nine sampling sites grouped into three biotopes: upstream and downstream of the Branca Waterfall, and tributary. The stomach contents of 3,263 individuals of 12 small species were examined according to the volumetric method. Altogether, 31 food items were identified. Overall seed consumption was greater in the rainy period, and the consumption of terrestrial plants was greater in the dry period. Hymenoptera was an important item in the diet, but the proportions in the consumption of this item was different between biotopes and periods. The consumption of Coleoptera and Isoptera was expressive only downstream of the Branca Waterfall in the rainy period, and aquatic plant was mostly consumed in the tributary in the dry period. Significant differences were detected in the diet composition between biotopes, hydrological periods and also the interaction between these two factors. Allochthonous resources were clearly the most consumed by the species in all biotopes, especially during the rainy period. The dietary overlap between species, although showing significant spatial and temporal differences, was low (0.4) for about 60% of species pairs. Thus, it is concluded that spatial and temporal changes in the utilization of food resources by small fish were related to physiographic differences of the channel and the surroundings, which contributed to the significance of seasonal changes in the diet, also reflecting the low dietary overlap between species. [ABSTRACT FROM AUTHOR]

In the Toledo metropolitan area there are many small headwater streams which suffer the influence of the urban development (pollution, deforestation, introduction of non-native species). The list of fish species in these sites is important for the knowledge on biodiversity in similar environments. Samples were taken bimonthly from October 2007 to February 2009 in three sites (headwater, middle and mouth) along of the three streams within urbanization gradient in the city of Toledo. A total of 27 fish species ascribed to 18 Genera, six Orders and 11 Families were collected, among which four species are non-native species, and seven are probably new to the science. [ABSTRACT FROM AUTHOR]

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., (© 2022 The Ecological Society of America.)

Corydoras Lacepède, 1803 is the most specious genus of Corydoradinae subfamily and many of its species are still unknown in relation to molecular cytogenetic markers. However, the diploid number and karyotypic formula were recorded for many species of this group. In current study, we provided the first cytogenetic information of Corydoras carlae Nijssen & Isbrücker, 1983, an endemic fish species from Iguassu River basin, Paraná State, Brazil. The individuals were collected in Florido River, a tributary of Iguassu River and analysed with respect to diploid number, heterochromatin distribution pattern, Ag-NORs and mapping of 5S and 18S ribosomal genes. The karyotype of this species comprises 46 chromosomes arranged in 22m+22sm+2st. The heterochromatin is distributed in centromeric and pericentromeric positions in most of the chromosomes, and also associated with NORs. The Ag-NORs were detected in the terminal position on the long arm of the metacentric pair 6. The double-FISH technique showed that 5S rDNA and 18S rDNA were co-localized in the terminal portion on the long arm of the metacentric pair 6. This condition of co-localization of ribosomal genes in Corydoras carlae seems to represent a marker for this species.