Dam removal is increasingly used to restore fish communities, since it helps reestablish historical migration routes and improves riverine habitat. However, dam removal success can be compromised by the upstream migration of invasive species. Round gobies (Neogobius melanostomus) were first documented in 2011 in the Rouge River, a tributary of the Detroit River in the Lake Erie basin. The 2012 removal of a dam on the lower branch of the Rouge River allowed the round goby to migrate upstream. We have tracked its upstream movement and the response of the fish community. In the first year, gobies moved 13.3 km upstream from the original dam site, followed by an additional 9 km over the next three years. Gobies arriving at new upstream locations were significantly larger than those residing downstream. Once gobies arrived, native johnny darters (Etheostoma nibrum) rapidly declined. Within two years, young-of-the-year gobies became prevalent at new sites and johnny darters disappeared. Our results indicate that the round goby is displacing johnny darter, changing the fish community. These findings suggest that invasive species movement should be factored into decisions about dam removal to consider potential negative impacts. Based on the changes we have observed in the lower Rouge, we advocate for rigorous pre- and post-monitoring of dam removal projects to document fish community response and evaluate whether the original goals of dam removal are being realized.