This cluster of papers focuses on the biogeography, conservation, and ecological dynamics of Neotropical freshwater fishes, with an emphasis on the Amazon River system. It covers topics such as fish biodiversity, impacts of hydropower dams, aging research using short-lived fish species, tropical river fisheries, electroreception in fishes, and the effects of habitat degradation on fish assemblages. The papers also explore the historical biogeography and evolutionary history of Neotropical freshwater fishes.