Silver redhorse (Moxostoma anisurum) is a catostomid species common to many rivers of eastern North America. We examined swimming activity and behaviour of silver redhorse during their upriver spawning migration when they encountered a vertical slot fishway. Twelve redhorse were tagged with PIT tags and monitored by an extensive PIT antenna array to determine location within the fishway. Individuals were also fitted with data logging accelerometer tags to determine location-specific activity and behaviour. Our study is one of the first applying accelerometer methods to characterize swimming behavior within a fishway. Our results may be used to modify existing fishways in order to improve passage efficacy for this and other species of similar biomechanical and physiological characteristics. 1 INTROCDUCTION River fragmentation is a ubiquitous occurrence in many rivers which are used as migratory routes by numerous diadromous and potamodromous species. Collectively, studies on fishway use have provided information on how fish ascend these facilities and where they encounter difficulties but did not provide information on the effort and behaviour of fish during ascent [1]. The understanding of biological criteria to inform fish passage design is therefore limited, partially due to the lack of understanding of biological motivators, cues, and constraints, as well as a lack of biological performance evaluations based on the physiological capacity and relative swimming ability of fish which may help to determine how these biotic factors relate to variation in fishway passage success and duration. The use of behavioural and physiological knowledge to inform resource management and conservation strategies [2] has great potential for applied fisheries issues. However, the application of such approaches to fishway science has been limited [3]. Most studies on fishway passage have focused on salmonids, but there is a need to examine other fish species. Catostomids frequently dominate fish abundance and biomass in North American rivers and are commonly encountered at fishways [4] due to their obligate migratory phase, increasing their susceptibility to river fragmentation [5]. The Richelieu River, Quebec, has a high abundance and diversity of catostomids, particularly of the Moxostoma genus, thus providing a unique a good model for the study of fish passage behaviour. Animal movement is generally achieved through muscle contraction, which leads to body and/or limb