What Ontario is Doing

To prevent these unwanted invaders from coming into the province, Ontario has regulated four species of Asian carp (Silver Carp, Bighead Carp, Grass Carp, Black Carp) as prohibited under the Invasive Species Act. For more information on the Invasive Species Act and Regulations visit www.ontario.ca/invasionON.


Asian carps were brought from Asia to North America in the 1960s and 70s. Since then they have migrated north through U.S. waterways towards the Great lakes. Preventing Asian carps from spreading into the Great Lakes is the best way to prevent harm to Ontario’s native fish species.

Asian carps (Silver Carp, Bighead Carp, Grass Carp, Black Carp):

  • Are successful invaders that have replaced native species in areas of the Mississippi River and its tributaries.
  • Make up more than 50 per cent of the fish by weight in some parts of the Illinois River.
  • Consume up to 40 per cent of their body weight each day, this leaves little food for native fishes to eat.
  • Can grow more than 25 centimetres in their first year.
  • Typically weigh two to four kilograms, but can weigh up to 40 kilograms and reach more than a metre in length.
  • Reproduce rapidly.

Impacts of Asian carps

Asian carps prefer cool to moderate water temperatures, like those found near the shores of the Great Lakes. If Asian carps become established in Ontario waters, they could potentially eat the food supply that our native fish depend on and crowd them out of their habitat. The decline of native fish species could damage sport and commercial fishing in Ontario, which brings millions of dollars a year into the province’s economy. The term “Asian carps” includes four species: Bighead, Silver, Grass and Black Carp. Bighead Carp and Silver Carp are the species that have spread the most aggressively and can be considered one of the greatest threats to the Great Lakes. Silver Carp are a hazard for boaters. The vibration of boat propellers can make Silver Carp jump up to three metres out of the water. Boaters and water-skiers in areas of the Mississippi and Illinois rivers have been seriously injured by jumping fish.

How to identify Asian carps

Bighead and Silver Carp represent the most severe threat to Ontario water.

Bighead Carp

  • Typically two to four kilograms; up to 40 kilograms in weight and more than a metre in length.
  • Very large head and toothless mouth.
  • Adult fish are dark grey with dark mottling.
  • Eyes sit below the mouth.

Silver Carp

  • Smaller than Bighead Carp.
  • Light silver in colour with a white belly.
  • Eyes sit below the mouth.

Grass Carp

  • Large scales that appear crosshatched.
  • Eyes sit even with the mouth.

Black Carp

  • Closely resembles the Grass Carp.
  • Weigh up to 36 kilograms (80 pounds) and exceed 1.5 metres (5 feet) in length.
  • Large scales with dark edges appear crosshatched.
  • Eyes sit even with the mouth.

Common Carp

Be sure not to confuse Asian carps with Common Carp. Common Carp are originally from Asia but were introduced to Canadian waters over 100 years ago, and are commonly mistaken for Asian carps. This diagram shows the key identification features to look out for.

What You Can Do

  • Learn how to identify Asian carps and how to prevent the introduction or spread of these unwanted species.
  • Never buy or keep live Asian carps. It is against the law to keep an Asian carp as a pet, use it as bait, or have a live Asian carp in your possession.
  • Don’t release any live fish into Ontario lakes or rivers. If you are fishing and incidentally catch an Asian carp, you must destroy it. Do not return it to the water.
  • If you have any information about the illegal importing, distribution or sale of live Asian carp, report it immediately to the MNRF TIPS line at 1-877-TIPS-MNR (847-7667) toll-free anytime. You can also call Crime Stoppers anonymously at 1-800-222-TIPS (8477).
  • If you’ve seen an Asian carp or other invasive species in the wild, please contact the toll free Invading Species Hotline at 1-800-563-7711, or visit EDDMapS Ontario to report a sighting.


OFAH/OMNRF Invading Species Awareness Program. (2012). Asian Carps. Retrieved from: www.invadingspecies.com.
This factsheet may be reproduced for non-commercial purposes.

Header photo by Kate Gardiner | Fish illustrations © Joe Tomelleri