Round goby Neogobius melanostomus is expanding its range within Illinois. Prior to 2004, the round goby existed primarily in the Lake Michigan waters of Illinois and was slowly moving inland via the Illinois Waterway. Two fish community monitoring programs, administered by the Illinois Natural History Survey's Illinois River Biological Station, have detected this fish species as it further expanded its range in the Waterway. Although little is known how this non-native benthic fish could threaten ecosystems in Illinois, the rate of invasion appears to be quickening.