Supersized Goldfish Could Become Superinvaders

Biologists counted more than 20,000 goldfish in a single urban pond the size of two basketball courts just west of Toronto. Some of the fish had grown into three-pound giants, and were probably descended from dumped pets. Invasive goldfish are flourishing in thousands of ponds built in the past 40 years in cities around North America.

Ecologists at the University of Toronto and the DFO are investigating if and how these ponds are selecting for extra- tolerant fish, which could help native fish in the Great Lakes. Nicholas Mandrak, a University of Toronto Scarborough biology professor working on the project, thinks that creating superinvaders that are likely to have greater impacts in the wild under climate change is a good idea.