The study examines the rapid changes in riverine fish communities across the Palaearctic, Nearctic, and Australasia realms, using a compilation of 4,476 time series from 1957 to 2019. It finds that community composition has changed significantly, with a 30% decline in community similarity per decade, characterized by shifts in dominant species. Total abundance and species richness increased by 13% and 7% per decade, respectively, while the proportion of non-native species declined. These changes are driven by past and recent anthropogenic pressures, with higher past pressures leading to faster increases in abundance and richness, but also contributing to the establishment of non-native species. Recent increases in anthropogenic pressures have had mixed effects, with antagonistic impacts on native and non-native species. The study highlights the importance of considering both the timing and magnitude of human impacts to understand community changes and inform conservation efforts.The study examines the rapid changes in riverine fish communities across the Palaearctic, Nearctic, and Australasia realms, using a compilation of 4,476 time series from 1957 to 2019. It finds that community composition has changed significantly, with a 30% decline in community similarity per decade, characterized by shifts in dominant species. Total abundance and species richness increased by 13% and 7% per decade, respectively, while the proportion of non-native species declined. These changes are driven by past and recent anthropogenic pressures, with higher past pressures leading to faster increases in abundance and richness, but also contributing to the establishment of non-native species. Recent increases in anthropogenic pressures have had mixed effects, with antagonistic impacts on native and non-native species. The study highlights the importance of considering both the timing and magnitude of human impacts to understand community changes and inform conservation efforts.