The round goby, Neogobius melanostomus, is a non-native fish species. They are known for their aggressiveness and the characteristic black spot on the dorsal fin. Originally found in Eurasia, particularly in the Black Sea, the Sea of ​​Azov and the Caspian Sea. They are capable of living in both fresh and salt water, making their ability to thrive almost anywhere possible. After first being discovered in the St. Clair River in 1990, the invasive species now calls the U.S. Great Lakes home. It is believed that the round goby was first brought here by international merchant ships. Within 14 years, they have managed to inhabit all five great lakes and are beginning to travel inland. The round goby is affecting the ecology of the Great Lakes and there have been several environmental impacts. There is also evidence that the round goby is increasing its range in unanticipated ways (Kornis et al., 2012). That the round goby spread so rapidly is believed to be due to a large degree of genetic variation and multiple areas where they were accidentally brought into the United States (Kornis et al., 2012). The feat of spreading so rapidly is also due to the high success rates in fertilization and hatching of eggs. Round gobies are known to be multiple breeders. They are able to lay eggs every three to four weeks during the months of April to September. The male will guard approximately 10,000 eggs from multiple females. Protecting nests from predators helps their success rate, which has been measured as high as 95% (Charlebois et al., 1997). The round goby has been studied primarily for its environmental impact. The round goby consumes smaller fish as prey, but also eggs of larger fish (Kornis et al., 2013). Specifically, in the St. Lawrence, researchers comparing invertebrate populations before and after round goby invasion found statistically lower predatory macroinvertebrate biomass as round goby concentrations increased (Kipp and Ricardi, 2012). . This is decreasing the numbers of its larger predatory fish, but also the food sources for similar-sized fish and other aquatic animals. As adults, round gobies fill the niches of native species and also take over spawning grounds.