The Round Goby

The Round Goby is a small, bottom-dwelling invasive fish. Native to the Black and Caspian seas in eastern Europe, it was first found in North America in 1990 in the St. Clair River north of Windsor, Ontario. Researchers believe the fish was brought to North America in the ballast water of ships from Europe. The Round Goby can spread fast due to its ability to spawn up to 3 times a season and produce upwards of 5000 eggs.



Round goby prefer waters with rocky and sandy bottoms. They feed aggressively on insects and other small organisms found on lake and river bottoms. Adult round goby eat large quantities of zebra and quagga mussels, and occasionally small fish and fish eggs.

Their eating habits along with their reproductive capabilities have the potential to harm the sport fish populations as they compete for food and by eating the eggs and young.

Scientists also believe that the Round Goby is linked to outbreaks of botulism type E in Great Lakes fish and fish-eating birds. The disease is caused by a toxin that may be passed from zebra mussels, to goby, to birds, resulting in large die-offs of fish and birds.

It is however important to be able to distinguish between our native fish - the Sculpin and the Round Goby. There are several differences however the easiest two are that the Round Goby has a distinct black dot on its dorsal fin whereas the Sculpin does not and the Round Goby has a fused single scallop looking Pelvic Fin whereas the Sculpin has two separate Pelvic Fins.

If you’ve seen a round goby or other invasive species in the wild, please contact the toll- free Invading Species Hotline at 1-800-563-7711, or visit Ontario's Invasive Species Awareness Program to report a sighting.