Motivation: We compiled a global database of long-term riverine fish surveys from 46 regional and national monitoring programmes and from individual academic research efforts, with which numerous basic and applied questions in ecology and global change research can be explored. Such spatially and temporally extensive datasets have been lacking for freshwater systems in comparison to terrestrial ones. Main types of variables contained: The database includes 11,386 time-series of riverine fish community catch data, including 646,270 species-specific abundance records, together with metadata related to the geographical location and sampling methodology of each time-series. Spatial location and grain: The database contains 11,072 unique sampling locations (stream reach), spanning 19 countries, five biogeographical realms and 402 hydrographical basins worldwide. Time period and grain: The database encompasses the period 1951-2019. Each timeseries is composed of a minimum of two yearly surveys (mean = 8 years) and represents a minimum time span of 10 years (mean = 19 years). Major taxa and level of measurement: The database includes 944 species of rayfinned fishes (Class Actinopterygii). Software format: csv. Main conclusion: Our collective effort provides the most comprehensive long-term community database of riverine fishes to date. This unique database should interest ecologists who seek to understand the impacts of human activities on riverine fish biodiversity and to model and predict how fish communities will respond to future environmental change. Together, we hope it will promote advances in macroecological research in the freshwater realm.

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Flow-dependent fish specialists require specific conditions for reproduction, so the success and reproductive intensity of these animals are determined by the flood regime. Thus, this study investigated the spatial and temporal reproductive patterns of fish, especially migratory Prochilodus species (flow-dependent specialists) in an unusual period of low flow in the Pará River sub-basin, one of the main tributaries of the upper São Francisco River. For this, ichthyoplankton collections were carried out between November 2013 and February 2014. Data were analysed considering the spatial and temporal variations in density of eggs and larvae for the upper, middle, and lower portions of the Pará River sub-basin, and correlating this to some environmental variables. The results showed that the small headwater stretch of the Pará River is one relevant spawning area for migratory fish species. However, this area is isolated by the Cajuru reservoir, which makes it uncertain the recruitment of these embryos, due to interruption of natural drift between spawning/nursery areas caused for reservoirs.Larvae of newly hatched migratory species found in tributaries of the lower Pará River sub-basin also indicate these species use these tributaries as spawning grounds and migratory routes. The period in which the research was conducted represented the most atypical low flow, one in the last 75 years, resulting in the low variability in the environmental parameters. Although few parameters increased briefly in this low flow period influenced by greater rainfall in December, this precipitation was possibly responsible for the final gonadal maturation and spawning of migratory species.

Neotropical Rivers host a highly diverse ichthyofauna, but taxonomic uncertainty prevents appropriate conservation measures. The Doce River Basin (DRB), lying within two Brazilian threatened hotspots (Atlantic Forest and Brazilian Savanna) in south-east Brazil, faced the worst ever environmental accident reported for South American catchments, due to a dam collapse that spread toxic mining tailings along the course of its main river. Its ichthyofauna was known to comprise 71 native freshwater fish species, of which 13 endemic. Here, we build a DNA barcode library for the DRB ichthyofauna, using samples obtained before the 2015 mining disaster, in order to provide a more robust biodiversity record for this basin, as a baseline for future management actions. Throughout the whole DRB, we obtained a total of 306 barcodes, assigned to 69 putative species (with a mean of 4.54 barcodes per species), belonging to 45 genera, 18 families, and 5 orders. Average genetic distances within species, genus, and families were 2.59, 11.4, and 20.5%, respectively. The 69 species identified represent over 76% of the known DRB ichthyofauna, comprising 43 native (five endemic, of which three threatened by extinction), 13 already known introduced species, and 13 unknown species (such as Characidium sp., Neoplecostomus sp., and specimens identified only at the sub-family level Neoplecostominae, according to morphological identification provided by the museum collections). Over one fifth of all analyzed species (N = 16) had a mean intraspecific genetic divergence higher than 2%. An integrative approach, combining NND (nearest neighbor distance), BIN (barcode index number), ABGD (automatic barcode gap discovery), and bPTP (Bayesian Poisson Tree Processes model) analyses, suggested the occurrence of potential cryptic species, species complex, or historical errors in morphological identification. The evidence presented calls for a more robust, DNA-assisted cataloging of biodiversity-rich ecosystems, in order to enable effective monitoring and informed actions to preserve and restore these delicate habitats.

The Black-collared Swallow, Pygochelidon melanoleuca, is a Critically Endangered species in the state of Minas Gerais, Brazil, where its distribution remains poorly known. Here we present novel occurrence records in the Paranaíba, São Francisco and Jequitinhonha river basins, and we discuss the conservation of this species in the region.

The present study provides the length‐weight relationship (LWR) for 21 fish species from eight rivers from Rio Doce River basin, Minas Gerais States, Brazil. Fishes were collected between August 1991 and September 2017, with gillnets, hand nets, cast nets and trawl nets. Standard length and total weight were measured for the LWR, which allometric coefficients b varied from 2.621 to 3.146.

Salvador-Jr, L.F., Salvador, G.N. and Santos, G.B. 2009. Morphology of the digestive tract and feeding habits of Loricaria lentiginosa Isbrücker 1979 (Loricariidae) in a Brazilian reservoir -Acta Zoologica (Stockholm) 90 : 101-109.The present study describes some aspects of the morphology of the digestive tract and the feeding patterns of Loricaria lentiginosa . Sixty-three specimens with gut contents were captured quarterly from November 2001 to August 2002 in Porto Colômbia reservoir, Rio Grande basin, southeastern Brazil. The species has bicuspid teeth inserted in the lips, unicuspid teeth in the dentary bone and pharyngeal teeth, besides having short, numerous and slightly separated gill rakers. The stomach is rudimentary and the intestine is relatively short (Intestinal Quotient = 1.32 ± 0.15). Molluscs, especially bivalves, represented the most important item on the diet of this species, followed by organic matter. The characteristics of the digestive tract as well as the dietary pattern, suggest that L. lentiginosa is able to explore bottom food resources, being classified as benthophagous with a tendency to malacophagy, and utilizing organic matter as an associated or additional food resource. Loricariidae species are able to use not only algae, sediment and detritus, but also plant and invertebrate items.

The introduction of invasive species is a significant threat to freshwater ecosystems and is changing the biogeographic patterns of fish species, leading to homogenization of fish fauna. The ability to predict potential invasions is critical in conservation biology to avoid further biodiversity loss. Ecological niche modelling has become an important tool in biological invasion studies. However, some introduced species can spread to habitats that are different from those in their native range. A framework based on niche shifts and ecological niche models was used to show that Pterygoplichthys ambrosettii, an armoured catfish, commonly known as ‘pleco', and native to the middle‐lower Paraná river, has expanded its niche by 27% and is now occupying a new range of environmental conditions. This species has experienced a niche shift from its original habitat and has started to occupy new areas of the Upper Paraná river basin and the São Francisco basin in Brazil. Models built using both native and non‐native areas were not able to predict the invaded habitats, and in either the native or non‐native areas the cross‐validation procedures corroborate the niche expansion hypothesis.