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Reports the invasion of Xiphophorus hellerii in Brazilian streams, indicating risks to native fish species.
Biological invasions threaten freshwater biodiversity, particularly in anthropogenically impacted ecosys-tems. We report the first record of the fish Xiphophorus hellerii Heckel, 1848 in the Piquiri river basin (Upper Paraná), which was found in recent surveys, and investigate its distribution in Brazilian streams, using secondary data. We recorded 19 individuals in the Piquiri river basin. The results indicate predominance of occurrences in metropolitan areas, totalling 76 records in Brazil, likely linked to aquarium releases. We hypothesize that channelized urban streams may facilitate establishment by increasing environmental stressors, and we highlight the risks to the native fish fauna by the invasive X. hellerii .
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Begnini et al. (2026) studied this question.
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