The study of fish communities across habitats of a meta-ecosystem can help determine which species provide coupling between meta-ecosystem components. A lake coupled with its floodplain form a meta-ecosystem with diverse habitats, which generates environmental heterogeneity favoring species that differ in their functional traits. Nonetheless, some species move across macrohabitats, generating habitat coupling. The Generalist Module Hypothesis in food web ecology advances that body size is a key predictor of which species drive coupling and energy exchange in a meta-ecosystem, with larger organisms contributing more than smaller organisms. In the context of fish communities in a lake-floodplain meta-ecosystem, other functional traits (e.g., reproductive timing, sensory traits, diet, and habitat preferences) should also influence the likelihood of floodplain utilization, and thus habitat coupling. We sampled fish communities in fluvial Lake Saint Pierre (Quebec, Canada) and its floodplain We used a joint species distribution model to examine how fish community structure responses to environmental variaionwere modified by functional traits This analysis helped identify which fish species or functional groups might provide coupling between habitats in a lake-floodplain meta-ecosystem.