What Ontario is doing

To prevent this unwanted invader from coming into the province, Ontario has regulated red swamp crayfish (Procambarus clarkia) as a prohibited invasive species under the Invasive Species Act, 2015.

Learn about the Invasive Species Act and regulations.


Red swamp crayfish is an aggressive invasive crayfish. They are found in various freshwater habitats with muddy or sandy bottoms and a large amount of organic debris. They can tolerate a wide range of:

  • salinities
  • pH
  • oxygen levels
  • temperature
  • pollution

Like other crayfish, they are considered an ecosystem engineer, capable of impacting ecosystem processes with the potential to affect all species in the area.

Red swamp crayfish are commonly raised for human consumption and have been reportedly used as bait by anglers. Sometimes sold as a “freshwater lobster,” they are kept as aquarium pets due to their deep red colour.


Red swamp crayfish are native to the southeastern United States, specifically the Gulf Coast from Florida to Mexico and the Mississippi River to southern Illinois and Indiana.

Red swamp crayfish have been introduced to Europe as well as many other U.S. states, including the watershed of Lake Michigan and into the Sandusky Bay of Lake Erie in Ohio in 1967.

Although currently not found in Ontario waters, the population in the Sandusky Bay is slowly expanding.

View an up-to-date distribution map of red swamp crayfish in North America.

Impacts of red swamp crayfish

The diet of the red swamp crayfish can accumulate large toxins that may be transferred up the food web.

In areas where red swamp crayfish populations grow large, their feeding behaviors may reduce the density of aquatic plants and decrease critical habitat in the ecosystem.

They may also overconsume species such as amphibians, small fish and molluscs while outcompeting native crayfish for these resources.

Burrows built by red swamp crayfish can destabilize stream banks or human infrastructure.

The diet of the red swamp crayfish can accumulate large toxins that may be transferred up the food web.

How to identify red swamp crayfish

The adult crayfish are 5.5 to 12 cm long. The adult’s body is also dark red, and the claws and head are elongated.

The head, claws and mid-body segment are covered in small red bumps.

What you need to know

  • Learn how to identify red swamp crayfish and how to prevent the introduction or spread of this animal to Ontario’s waterways.
  • It is against the law to import, possess, deposit, release, transport, breed/grow, buy, sell, lease or trade red swamp crayfish in Ontario.
  • Never buy, keep or breed red swamp crayfish as a pet or for any other purpose. They may be listed under synonyms such as freshwater lobster.

Reporting illegal activity

If you have any information about the illegal importation, distribution or sale of red swamp crayfish, report it immediately to either:

If you’ve seen red swamp crayfish or another invasive species in the wild, please:


A red swamp crayfish on concrete

Photo: Luc Hoogenstein, Wikimedia Commons

A red swamp crayfish on mud and rocks

Photo: U.S. National Parks Services, Wikimedia Commons