The round goby is a small, aggressive bottom-dwelling fish. They usually grow three to six inches long, but can grow up to ten inches. The young are solid gray and adults are light grey with dark blotches. They resemble sculpins, which are native bottom-dwelling fishes.
Body Shape and Fins
Large head, bulging eyes and torpedo-shaped body. They have a single scallop-shaped (fused) pelvic fin. No other native fish in the Great Lakes have a fused pelvic fin. The dorsal fin has an obvious black spot.
The round goby is an aggressive bottom-dwelling fish that feeds on a variety of macroinvertebrates, fish eggs and fry. Adults aggressively defend spawning sites and can spawn several times per year. Round gobies have been found at densities up to 20 individuals per square yard. They have a well developed sensory system that enhances their ability to detect water movement, allowing them to feed in complete darkness—a competitive advantage over other fishes.
Origin and Spread
The round goby is native to the freshwater region of Europe’s Black and Caspian Seas. The species was first confirmed in the United States’ St. Clair River in 1990. By 1999, the species was found in several locations within Lake Superior’s Duluth Harbor in Minnesota.
Don't be fooled by these look-alikes
Round goby (Neogobius melanostomus) is a prohibited invasive species, which means it is unlawful (a misdemeanor) to possess, import, purchase, transport, or introduce this species except under a permit for disposal, control, research, or education.
Threat to Minnesota Waters
Round goby infestations cause recreational, economic and ecological damage—changing how residents and visitors use and enjoy Minnesota waters.
- May attack and take Anglers' bait, making it nearly impossible to land other preferred fish species.
- Out-compete native fishes for food and spawning habitat.
- Eat the eggs and fry of native fishes.
- May aid the spread of avian botulism.
What you should do
People spread the round goby primarily through the improper use and disposal of live bait.
Whether or not a lake is listed as infested, Minnesota law requires water recreationists to:
- Clean watercraft of all aquatic plants and prohibited invasive species.
- Drain all water by removing drain plugs and keeping them out during transport.
- Dispose of unwanted bait in the trash.
- Dry docks, lifts, swim rafts and other equipment for at least 21 days before placing equipment into another water body.
There is no known effective population control for round goby in natural water bodies at this time.