Freshwater fishes are among the most imperiled taxa in the world. Over 30% of freshwater fishes in North America, and over 25% in Canada, are of conservation concern. The primary current stressors related to imperilment are habitat alteration and destruction, and aquatic invasive species. While native species are declining, aquatic invasive species are spreading in North America. These trends are expected to be exacerbated in the future by stressors such as climate change and human population growth. Biotic homogenization - the increasing similarity of communities across the landscape and the globe - is a result of these trends and is an indicator of biodiversity loss. The objective of my research program is to better understand the patterns, processes, and stressors of Canadian freshwater fishes at multiple taxonomic and geographic scales. Such knowledge is essential for the conservation, protection, and recovery of freshwater fish biodiversity in Canada.