Bluegill is a popular game fish in North America. Despite its popularity among anglers for its tasty and flavored meat and increasing demand for fish, its current food is made for largemouth bass and requires two growing seasons to reach food size. This study investigates growth characteristics, gut microbiota compositions, and gene functions of juvenile bluegill fed a commercial and an alternative diet in a recirculating system. In a completely randomized experimental design, with three tanks per diet, bluegill with an initial average weight of 12.67±0.14 g was fed for six weeks. The fish were fed two times daily to apparent satiation, and growth parameters were monitored. The results revealed the ability of the fish to utilize both diets, but the responses differed between the two diets. Growth, feed conversion ratio, and specific growth rate were significantly affected by dietary treatments (P<0.05). The hypolipidemic effect was observed; elongation and desaturation of the C18:2n6 and C18:3n3 pathways were affected by dietary treatment affected by diets (P<0.05). The 16S rRNA data revealed Fusobacteria, Firmicutes, Proteobacteria, and Bacteroidota as the major bacterial phyla in the bluegill intestinal samples, and their relative abundance differs in the two diets. More information about the effect of the dietary treatments on gut microbiota and predicted functional gene families using PICRUSt2 will be presented.