Species At Risk

Northern Madtom

(Noturus stigmosus)


Northern Madtom
Northern Madtom occurrences map


The Northern Madtom is a small catfish that grows up to 13 centimetres in length. It has four pairs of large whiskers, called barbels, around its mouth that it uses to help find food at night. This fish is olive-grey to brown in colour, with three dark-coloured blotches on its back, two pale spots in front of the dorsal fin, and three or four dark crescents on the tail fin. The fins are pale with darker markings. There are sharp spines on the dorsal and pectoral fins and poison glands associated with the pectoral spines.

Action we are taking:


In Canada, the Northern Madtom is only found in Ontario in the St. Clair River, Lake St. Clair, the Detroit River, and the Thames River. It has not been seen in the Sydenham River since 1975.


The Northern Madtom usually lives in large creeks and rivers with a moderate to swift current, and a sand, gravel, or mud bottom. However, in Ontario, this fish has also been captured in the deeper waters of Lake St. Clair and the Detroit River. It prefers clean, unpolluted water but can tolerate slightly muddy water. Adults eat aquatic insects, crustaceans, and smaller fish. During the summer breeding season, Northern Madtoms normally build nests under large flat rocks and logs.


The main threat to the Northern Madtom is habitat destruction. This fish requires clean water in order to survive and can be harmed by pollution and soil that washes into the river from nearby urban and agricultural areas. Competition from non-native fish is also a potential problem.


The Northern Madtom is protected under Ontario’s Endangered Species Act and the federal Species at Risk Act.

What You Can Do to Help the Northern Madtom

  • The Ministry of Natural Resources tracks species at risk such as the Northern Madtom. You can use a handy online form to report your sightings to the Natural Heritage Information Centre. Photographs with specific locations or mapping coordinates are always helpful. nhic.mnr.gov.on.ca
  • Report any illegal activity related to plants and wildlife to 1-877-TIPS-MNR (847-7667).
  • Invasive species seriously threaten many of Ontario’s species at risk. To learn what you can do to help reduce the threat of invasive species, visit: ontario.ca/invasivespecies ; www.invadingspecies.com ; www.ontarioinvasiveplants.ca ; and, www.invasivespecies.gc.ca .
  • Volunteer with your local nature club or provincial park to participate in surveys or stewardship work focused on species at risk.
  • Private land owners have a very important role to play in species at risk recovery. If you find Northern Madtom in a watercourse on or adjacent to your property, you may be eligible for stewardship programs that support the protection and recovery of species at risk and their habitats.
  • Farmers and land owners can help improve fish habitat and keep Ontario’s water safe and clean by maintaining natural vegetation next to creeks and rivers, and keeping pollution and soil from washing into Ontario’s rivers. You can find more information about programs and funding assistance for eligible farmers from the Ontario Soil and Crop Improvement Association website at www.ontariosoilcrop.org/en/programs/species_at_risk.htm.
  • You can help improve the river habitat where the Northern Madtom lives in the Thames watershed by taking part in the annual Thames River Cleanup www.thamesrivercleanup.ca .
  • Find more information about all of the species at risk living in the Thames watershed at www.thamesriver.on.ca/Species_at_Risk/species_at_risk.htm.

Did you know?

The sharp spines and poison glands found on the pectoral fins of the Northern Madtom can cause a painful wound!

Did you know?

The Northern Madtom was only discovered in Ontario in 1963. This fish can be hard to find because it is extremely rare and only active at night.

Did you know?

The male Northern Madtom is a protective father. He guards the eggs and the newly hatched young fish and will refuse to abandon the nest even if disturbed.

Did you know?

The Northern Madtom is globally rare with fewer than 80 known populations on the planet.

The Endangered Species Act

Contact your local ministry office

Often the best source of local information on species at risk is your nearest ministry office. Call with your questions or concerns.