An angler near Dunnville, about a half hour south of Hamilton, didn't just hook a big one — the fisherman also managed to land a fish story that has all of North America's biologists and sport fishing enthusiasts talking.

Authorities with Fisheries and Oceans Canada and the Ontario of Ministry of Natural Resources have confirmed that the fish is a live Asian carp and it was caught close to the mouth of the Grand River, near Lake Erie.

Government biologists say the fish, measuring 110 centimetres and weighing 18.5 kilograms, was a grass carp, one of four species of Asian carp, including bighead, silver and black carp; all of which are illegal to possess as live fish in Ontario and Michigan.

Of particular concern are silver and bighead carp, which gorge on plankton — microscopic plants and animals that virtually all fish eat at some point. The carp reproduce prolifically, and the biggest can reach 100 pounds.

As a result, the fish are considered highly invasive and one of the biggest threats to the Great Lakes ecosystem and Ontario's $7 billion sport fishing industry.

However scientists say lab tests reveal the fish caught in the Grand River last month was sterile.

According to Fisheries and Oceans Canada, several U.S. states allow the stocking of grass carp in order to control aquatic plants. The states also require the fish to be sterilized in order to prevent them from reproducing.

Whether the fish is the leading edge of an invasion or a single escaped fish remains to be seen, but authorities with the Ontario Ministry of Natural Resources urge all fishermen to become familiar with the species and report any new discoveries to Ontario's Invading Species Hotline, at 1-800-563-7711.

Hugh MacIsaac, professor and director of the Canadian Aquatic Invasive Species Network at the Great Lakes Institute for Environmental Research, said it's not time to push the panic button.

He said this specific type of carp is used in states like a Michigan and New York to control of aquatic plants in places like ponds. They will not reproduce.

There have been about 10 records of them being in Ontario.  He said the much bigger threat is the big headed and silver carp.