Research into bivalve microbiomes has identified distinct microbial communities across tissue types, including the hemolymph, gills, and gut complex. The consistent presence of these microbial communities likely indicates that bivalve microbiomes play crucial roles in host physiology and have a functional role similar to those in vertebrates. The bivalve suspension-feeding strategy exposes these animals to a number of microbes, both free-living and particle associated. Some of these microbes are unlikely to become established as members of a particular community. Most research in this field has focused on marine bivalves, with little focus on freshwater species. The purpose of this study was to characterize the resident gill and gut microbial communities of the freshwater e astern e lliptio, Elliptio complanata. Mussels were collected from natural populations in the Delaware River. One subset of mussels was dissected immediately to isolate both resident and transient microbes associated with the gill and gut tissues. A second subset of mussels was placed into individual depuration chambers for 24 hours to allow animals to egest feces and transient microbes. After 24 hours, egested feces were collected, and gill and gut tissues isolated to characterize the resident microbial communities. Approximately 2/3 of mussels collected were gravid, therefore one demibranch containing eggs was also collected from a subset of mussels. Water samples were taken from the Delaware River to examine the pool of microbes from the natural water. All samples underwent DNA extraction, PCR, and 16S rRNA sequencing to identify the associated microbial communities. Data from this experiment will provide essential baseline knowledge of Elliptio microbial communities and inform future work investigating the dynamics of freshwater bivalve host-microbe interactions.