The Round Goby, Neogobius melanostomus, is a non-native fish species. They are known for their aggression and their characteristic black spot on their dorsal fin. Originally found in Eurasia, particularly in the Black Sea, Sea of ​​Azov and Caspian Sea. They are capable of inhabiting both fresh and salt water, allowing them to thrive almost anywhere. After first being discovered in the St. Clair River in 1990, the invasive species has now taken up residence in the United States Great Lakes. The round goby is believed to have been first introduced here by international transport ships. In the space of 14 short years, they were able to inhabit the five great lakes and began to travel inland. The round goby affects the ecology of the Great Lakes and has had several environmental impacts. There is also evidence that the round goby is expanding its range in unanticipated ways (Kornis et al. 2012). The fact that the round goby has spread so quickly is thought to be due to a high degree of genetic variation and multiple areas in which they were accidentally brought into the United States (Kornis et al., 2012). The feat of spreading so quickly is also due to their high success rates in fertilization and egg hatching. Round gobies are known to breed multiple times. They may spawn every three to four weeks from April to September. The male will guard around 10,000 eggs from several females. Protecting the nest against predators contributes to its success rate, which has been measured at up to 95% (Charlebois et al., 1997). The round goby has been studied primarily for its environmental impacts. The round goby consumes smaller fish as prey, but also consumes the eggs of larger fish (Kornis et al., 2013). More specifically, in the St. Lawrence, researchers who compared invertebrate populations before and after the round goby invasion found a statistically lower biomass of macroinvertebrate predators as the goby concentration increased. black spots increased (Kipp and Ricardi, 2012). This reduces the numbers of its larger predatory fish, but also reduces food sources for similarly sized fish and other aquatic animals. As adults, round gobies fill the niches of native species and also invade spawning grounds..