Sightings of Asian grass carp in two Toronto ponds have prompted the "biggest response in Canada to date" from Fisheries and Oceans Canada against the invasive species.

Crews have been searching the Leslie Street Spit area since two male carp in breeding condition were spotted on Tuesday. The fish were found in an enclosed pond in Tommy Thompson Park, which is located just minutes from downtown Toronto along the city's waterfront.

Officials are not yet sure how the two fish got there. Another Asian carp was discovered in the Don River in 2003, but it was sterile.

On Wednesday, four boats were deployed in the Leslie Street Spit area to search for more carp, but none were caught. Officials on each boat were equipped with an electro-fishing bone, an instrument that puts electricity in the water which stuns the fish, causing them to float up to the surface.

The fish are not harmed in the process. They are stunned long enough so that they can be captured. Officials said anything that looked like a carp would be captured, and anything that does not will be released. The two captured male carp are being examined at a fisheries lab in Burlington, Ont.

One of the Asian carp was approximately one-metre long, while the other was slightly smaller, Asian carp program manager Becky Cudmore told CTV Toronto on Wednesday.

Cudmore conducts research on the species for the federal Asian Carp Science Lab located at the Canada Centre for Inland Waters, a division of Fisheries and Oceans Canada.

"We're in an interesting position in that we can see the destructive behaviour that Asian carp are posing in the established environment in the United States," Cudmore said.

South of the border, the fish have been known to push out the native species, destroy commercial fishing nets and ruining wetland habitats, she said.

"We are in a unique position to try to prevent that in the Canadian waters of the Great Lakes, so that's our focus."

When two of the fish were spotted in Toronto, Fisheries and Oceans Canada teamed up with the Toronto Region Conservation Authority and Ontario Ministry of Natural Resources.

"It's a very formal system. We have all been trained," Cudmore told CTV Toronto of the protocol on Wednesday. Still, Cudmore said it's the "biggest response" the team of experts has implemented in Canada to date.

The reason for the urgency of the investigation is that the two giant fish were found close together, in a short period of time, meaning there may be others nearby.

Cudmore added that there's no need to panic, saying that there's no evidence of an invasion so far. She called the presence a "concern," but said there were no signs of spawning behaviour. Both fish found in Toronto are male, and there have been no sightings of female fish.

With a report from CTV Toronto’s John Musselman