Agencies from three levels of government sprang into action after two Asian grass carp, a highly invasive species of fish, were found in a pond near Toronto's waterfront.

The Toronto and Region Conservation Authority (TRCA) said Wednesday that its staff discovered the first fish on Monday while relocating fish from the pond at Tommy Thompson Park, where the city is constructing a nine-hectare wetland. The second fish was found Tuesday.

Fisheries and Oceans Canada officials remain on the scene, where they're looking for more signs of the species.

The federal agency, TRCA and Ontario's Ministry of Natural Resources and Forestry all sent officials to the scene, but nobody knows at this point how the fish made it into the pond.

Rick Portiss, of the TRCA, said grass carp feed on aquatic vegetation and would "chew up" much of the natural habitat that native species rely on.

Portiss said the fish can be "very disruptive" to the ecosystem, in this case a pond on the 500-hectare, man-made spit that juts five kilometres out into Lake Ontario from the city's waterfront.

Fish can weigh up to 40 kg

Asian carp is a catchall name for species of silver, bighead, grass, and black carp from Southeast Asia. The fish typically weigh two to four kilograms, but can weigh up to 40 kilograms. The species is known to eat up to 20 per cent of their body weight in plankton each day and can reproduce quickly.

The last time an Asian grass carp was found in a Toronto waterway was in 2003, when TRCA staff found one near the mouth of the Don River.

Earlier this month, government officials in the United States said they plan to spend nearly $60 million US over the next two years in the battle to prevent Asian carp from reaching the Great Lakes.

On its site, the TRCA says "where they have proliferated in parts of the United States, grass carp have had a negative effect on the ecosystem, as well as on the commercial and recreational fishery. Grass carp feed extensively on aquatic vegetation, often uprooting large areas of vegetation, thus depleting other native fish species."

TRCA asks that if you see an Asian carp, please call the Invading Species Hotline at 1-800-563-7711