Round Goby (Neogobius melanstomus)


The Round Goby is a small bottom-dwelling fish native to Eastern Europe, and is believed to have been transported to the Great Lakes in ballast water from shipping vessels1. It has spread rapidly since it was first detected in Lake St. Clair in 1990 and is now found in all the Great Lakes and a few inland lakes. Its movement has been aided by bait bucket transfer2. The Round Goby prefers rocky, shallow areas but is able to flourish in a wide range of habitat types and can also tolerate poor water quality1. Round Goby are currently found in the Credit River Watershed in two ponds in Hillsburgh and in the lower portion of the Credit River south of the Mississauga Golf and Country Club into Lake Ontario.


Measuring up to 25 cm and bearing resemblance to our native Mottled Sculpin, distinguishing characteristics of the Round Goby are its frog-like eyes, the black spot on its dorsal fin, and the fused pelvic fin on its belly2.

Photo of Fused Pelvic Fin

Ecological Threat

Round Gobies pose a threat to fish populations and food chains in invaded water bodies. They undergo rapid population growth and out-compete native fish species for food and spawning sites1. Round Gobies are able to spawn frequently and the males aggressively defend their nests. These characteristics result in relatively high numbers of offspring produced over a short period of time. Round Gobies also have very broad diets. They directly compete with several native fish species, such as darters, sculpins and Logperch, and are known to consume the eggs and fry of sportfish. They also compete for food sources such as invertebrates with native fish species. These characteristics enable the Round Goby to displace small native species from spawning, shelter, and forage areas, and become the dominant species in an area. Populations of Mottled Sculpin and Logperch have seen dramatic declines since the arrival of the Round Goby to the Great Lakes region2. CVC monitoring data at 2 sites in the lower river shows large declines in darters and other benthic fish where gobies are present but smaller declines in benthic fish at a similar site with no gobies. Finally, Round Gobies have also been implicated in spreading botulism outbreaks to birds and fish that consume them2.

In addition to ecological harm, Round Gobies can also have negative social and economic impacts. Some anglers consider them a nuisance due to their abundance and their habit of stealing bait. They have the potential to negatively impact both recreational and commercial fisheries through their impacts on aquatic food chains. There are also concerns that gobies may bio-accumulate toxins from feeding on Zebra or Quagga Mussels, which may be passed up the food chain to species that people consume.

Preventative Strategies

The best way to stop the spread of Round Goby starts with prevention. If travelling from Lake Ontario, where Round Gobies are currently abundant, please clean your boat and trailer and ensure your boat bilge and live wells are drained before travelling to another water body. Additionally, it is recommended that water from one lake or watercourse should never be transferred to another3. To help slow or restrict their spread, Round Gobies have been banned as baitfish and it is illegal to possess live specimens.

If you find a Round Goby anywhere in the Credit River watershed excluding the lower river between the Mississauga Golf and Country Club and Lake Ontario and two ponds adjacent to Station Street in Hillsburgh, please contact CVC via email.

Video: (Video created by Ontario’s Invading Species Awareness Program)


  1. Jude, D. J., Reider, R. H., and Smith, G. R. 1992. Establishment of Gobiidae in the Great Lakes basin. Can. J. Fish. Aquat. Sci. 49: 41 6-421.
  1. Ontario Federation of Anglers and Hunters (OFAH). “Round Goby”. Ontario’s Invading Species Awareness Program. Web. 26 July 2018.
  1. Ontario Ministry of Natural Resources (OMNR). 2012. “Round Goby (Neogobius melanostomus)”. Web. 26 July 2018.
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