Non-native species are a major driver of biodiversity loss. Aquaculture activities play a key role in introductions, including the escape of fishes from fish farm facilities. Here, the impact of flooding due to El Niño rains in 2015/2016 in the Lower and Middle Paranapanema River basin, southern Brazil, was investigated by evaluating fish escapes from 12 fish farms. The flooding resulted in the escape of approximately 1.14 million fishes into the river, encompassing 21 species and three hybrids. Non-native species were the most abundant escapees, especially Oreochromisniloticus (Linnaeus, 1758) and Coptodonrendalli (Boulenger, 1897) (96% of all fish). Only seven native fishes were in the escapee fauna, comprising 1% of all fish. Large floods, coupled with inadequate biosecurity, thus resulted in considerable inputs of non-native fish into this already invaded system.

The Paranapanema River is an important, extensively explored tributary of the Upper Paraná River basin. The fish fauna of the Paranapanema River has been investigated since the 1990s; however, no study has characterized the richness of fish species throughout the basin, including the main channel of the river, marginal lagoons, its tributaries, and sub-tributaries. Thus, we performed a review with 90 independent studies conducted at the upper, middle, and lower sections of the basin. We recorded 225 species, of which 165 were native, and 60 were non-native. We found that 77% of the species within the basin are composed by Siluriformes and Characiformes. Cichliformes had a significant number of non-native species established in impoundment sections of the basin. Incidence-Based Estimators (Bootstrap and Chao 2) demonstrated that the richness of native species is still underestimated. Some native (e.g., Hypostomus ancistroides) and non-native species (e.g., Plagioscion squamosissimus) are widely distributed in the basin, while others had a more restricted distribution. Among the registered species, the family Bryconidae had the highest number of representatives with threatened conservation status. In addition, we observed that the Capivara Reservoir and its tributaries were the most sampled regions, with the majority of studies performed in the Lower Paranapanema basin. The species richness recorded in large tributaries, such as Tibagi, Cinzas, Congonhas, and Pirapó rivers is critical for maintaining the fish fauna in the Paranapanema River. Our contribution may be used to support management actions and conservation strategies, as well as to indicate regions in the basin that need to be better inventoried.

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O aquarismo é um hobby praticado mundialmente com aumento de popularidade no Brasil nas últimas décadas. A soltura de peixes ornamentais em ambientes naturais é equivocada, sendo considerada introdução de espécies e crime ambiental. Dessa maneira, objetivou-se verificar a existência de registros de solturas disponíveis na web, na mídia social Youtube™ no Brasil. A busca por vídeos com situações de soltura ou descarte foi realizada entre julho e dezembro do ano de 2018, totalizando-se 616 horas de busca. Como resultado, obteve-se 48 registros de solturas, sendo as mais incidentes as regiões do Sudeste, Nordeste e Sul. São Paulo, Minas Gerais, Espírito Santo e Rio de Janeiro foram os Estados com maior número de registros. Registrou-se 33 táxons de peixes (18 gêneros e 15 espécies) e dois híbridos, sendo muitas delas espécies invasoras. A maioria dos praticantes não tem conhecimento sobre a ilegalidade do ato ou a possibilidade de impacto ambiental. O perigo das solturas ornamentais quanto à oportunidade de invasão biológica, a pressão de propágulo empregada e os conceitos equivocados sobre ecologia abordados nos vídeos são discutidos. Sugere-se a conscientização dos aquaristas e maior controle sobre o hobby, sendo as redes e mídias sociais uma nova ferramenta para os órgãos fiscalizadores detectarem distúrbios que possam prejudicar os ambientes naturais.

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The aim of this study is to report the presence of a three non-native hybrid long-whiskered catfishes (family Pimelodidae) in the Upper Paraná River basin, Brazil. Genetic analyses demonstrated that the three presumptive hybrids were a result of the crossbreeding of Pseudoplatystoma reticulatum (central Amazonas River basin and Lower Paraná River) and Leiarius marmoratus (Amazonas, Essequibo and Orinoco rivers), producing a hybrid commonly known in Brazil as cachandiá. The potential threat to biodiversity, due to possible genetic contamination, competition and predation of wild stocks, of such artificially produced hybrid fishes is discussed.

Abstract. Garcia DAZ, Vidotto-Magnoni AP, Costa ADA, Casimiro ACR, Jarduli LR, Ferraz JD, De Almeida FS, Orsi ML. 2019. Importance of the Congonhas River for the conservation of the fish fauna of the Upper Paraná basin, Brazil. Biodiversitas 20: 474-481. The Upper Paraná River basin is among the most fragmented watersheds in the world. The Congonhas River belongs to this drainage system, which has its mouth in the Capivara Reservoir and can be considered the largest tributary free-from-dam, becoming important for the maintenance of fish species richness. In order to know more about the species present in this tributary, we aimed to provide an inventory of fish fauna of the Congonhas River and reproductive strategies to determine whether the river is used by migratory species and whether there is a longitudinal variation in the fish assembly. These findings will provide subsidies to contribute to the implementation of policies to protect biodiversity. Samplings occurred in the upper, middle and lower stretches of the Congonhas River during four periods between 1991 and 2011. Fishes were captured using gill nets from 2 to 14 cm mesh sizes between opposite knots and cast nets, identified and categorized according to their reproductive strategies. A total of 4,640 individuals belonging to 63 species, of which 79.4% consisted of Characiformes and Siluriformes were captured. Furthermore, 14% of fish were long-distance migratory species (e.g., Piaractus mesopotamicus, Megaleporinus obtusidens, Prochilodus lineatus, Salminus brasiliensis, Pinirampus pirinampu, and Pseudoplatystoma corruscans). In addition, there was an increase in the fish species richness from upstream to downstream. Management actions such as prohibition of fishing, rehabilitation of riparian vegetation, and protection of the basin against dam construction will reduce anthropogenic impacts on the ecosystem. The Congonhas River highlights the importance of preserving lotic environmental for the conservation of migratory and non-migratory Neotropical fish diversity into a heavily modified watershed.