Nile Tilapia Captured in the Grand River

Chris Bunt of Biotactic Fish & Wildlife Research recently captured what appears to be a Nile Tilapia (Oreochromis niloticus), an exotic African fish, in a fish ladder on the Grand River near Hidden Valley. It’s believed to be the first record of the species in Canada and raises the possibility the invasive fish could threaten native species. The fish has been sent to Fisheries and Oceans for testing to determine whether the 28 cm fish had been in the Grand for only a few weeks or much longer.

Tilapia multiply quickly and are omnivorous. They are capable of consuming enough aquatic vegetation to significantly harm habitats for native species if they became established. However, tilapia are warmwater fish, unable to tolerate temperatures less than 8 °C, so they would be unlikely to survive through the winter.

Bunt suspects the tilapia was released into the river either by a aquarium hobbyist who no longer wanted it, or someone who bought it to eat, then didn’t have the heart to kill it. Bunt said the possibility of surviving overwinter isn’t completely impossible because groundwater and/or water treatment plant discharges can create plumes of warmer water where tilapia could seek refuge. Either way, he said the discovery should be a reminder never to release live fish into the wild. (Original article published in The Waterloo Region Record June 26, 2010; written by Brian Caldwell, Record staff).