<p>Riverine cypress swamps in the southeastern U.S. support diverse fish assemblages. However, environmental degradation has resulted in the loss of 72% of the original bottomland wetlands. Few studies have focused on fish-habitat associations in riverine cypress swamps, and none have been conducted near the northern limit of the cypress-tupelo swamp range. Therefore, our objectives were to evaluate spatiotemporal patterns in fish assemblage structure, abundance, and habitat associations in a managed, riverine cypress swamp in southern Illinois. The fish assemblage in Buttonland Swamp was sampled using electrofishing during 2020–2022. Buttonland Swamp was divided into macrohabitats and microhabitats defined by geomorphic features (pond, river, and side channels) and vegetation. Non-metric multidimensional scaling and analysis of similarities were used to evaluate spatiotemporal patterns in fish assemblage structure. Indicator species analysis was used to identify prominent species associated with habitats, seasons, and years. Fish assemblage structure differed among microhabitats, microhabitats within macrohabitats, and microhabitats within seasons. Maintaining habitat diversity appears to be important for maintaining the diverse fish assemblage in Buttonland Swamp.</p>