Margined Madtom
The margined madtom is a small, nocturnal catfish at the northern edge of its range in Canada, found in a handful of rivers and lakes in Ontario and Quebec. It's rarely targeted deliberately — most encounters come from micro-fishing enthusiasts or researchers.
Its protected status makes it more a fish to know and release carefully than one to pursue.
Also known as chat-fou liséré
- Yellow to slate-grey above, cream or white below; no blotches or saddle marks on the back — a key distinction from other madtoms.
- Dorsal and caudal fins are light brown or yellow with distinct black edges; the adipose fin runs continuously into a square-edged tail.
- Upper jaw projects slightly beyond the lower jaw; pectoral spines carry large rear-facing teeth and can deliver a painful sting similar to a bee sting.
- Adults typically reach about 100 mm (4 in); maximum size is around 15 cm (6 in).
What to know
Habitat Distribution
- Native to Canada at the northernmost limit of its range; Canadian populations are restricted to a few sites in Ontario and Quebec.
- In Quebec, found in Gatineau Park, the Gatineau River, Rivière Lapêche, and along the Ottawa River in Hull and Papineau counties.
- In Ontario, recorded from the Fall River, Mississippi River, and Bolton Creek in Lanark County, and from Lake Joseph, Lake Rosseau, and Lake Muskoka in the Muskokas — though Ontario populations are considered introduced.
- Prefers rocky riffles and runs in clear, fast-flowing creeks and small to medium rivers with cobble, boulder, or coarse gravel bottoms.
Key Locations
- Gatineau Park and Gatineau River, Quebec — the longest-documented Canadian population, first recorded in 1971.
- Rivière Lapêche, Gatineau County, Quebec — confirmed capture sites from the 1980s.
- Ottawa River (Quebec side), Hull and Papineau counties — known occurrence area.
- Mississippi River and Fall River, Lanark County, Ontario — recorded Ontario sites, though populations here are considered introduced.
- Lake Muskoka, Lake Rosseau, and Lake Joseph, Ontario — lake-habitat records in the Muskoka region.
Specific Spots
- Rocky riffles with cobble or boulder substrate — madtoms tuck under flat rocks and in crevices during daylight hours.
- Fast runs where current breaks behind large rocks create low-velocity pockets; these are the spots where madtoms forage after dark.
- Undercut banks and woody debris in clear, swift reaches give additional daytime cover in smaller streams.
Margined Madtom FAQ
Answers from onWater's species guide.
What are the best lures and bait for Margined Madtom?
Small pieces of earthworm fished on the bottom after dark, near rocky cover, are the most practical bait, matching the invertebrate prey the fish naturally hunts at night.
How do you catch Margined Madtom?
Because the margined madtom is listed as Threatened under SARA, deliberately targeting it is not appropriate. Incidental captures during micro-fishing or electrofishing surveys do occur; handle any accidental catch with wet hands, avoid the pectoral spines, and release the fish immediately at the point of capture.
What do Margined Madtom eat?
Feeds primarily on aquatic insect larvae, mayfly nymphs (baetids), midge larvae (chironomids), and blackfly larvae (simuliids) make up the bulk of the diet. For micro-fishing, small natural baits like a tiny piece of worm fished on the bottom near rocks closely mimics this forage.
Where do Margined Madtom live?
Native to Canada at the northernmost limit of its range; Canadian populations are restricted to a few sites in Ontario and Quebec. In Quebec, found in Gatineau Park, the Gatineau River, Rivière Lapêche, and along the Ottawa River in Hull and Papineau counties.
See it in the app
Most maps show you water.
onWater shows you Margined Madtom.
- 01 · Species map filter
Map every Margined Madtom water
Pick Margined Madtom and the map zeroes in on the waters they call home. No more guessing which lake holds them.
- 02 · Waterbody species
Tap any water. See what lives there.
Species, behavior and seasonal patterns for every lake, river and pond, before you leave the driveway.
- 03 · Angler Intelligence
Ask how to catch Margined Madtom
Tactics, gear and timing from onWater's AI fishing guide, tuned to the species and the water you're on.
Stop guessing where Margined Madtom are.
Open the map, filter by Margined Madtom, and head to water that holds them. Download onWater and plan your next trip in minutes.
- Species map filter
- Angler Intelligence
- Fishing journal
Explore other species
Trout, bass, salmon, panfish and everything in between. Each guide unpacks the behavior, seasons, and tactics that put fish in the net.
No species information available.
Smarter Fishing Starts in the App.
onWater Fish gives you everything you need to plan smarter, fish better, and own every trip from first cast to last.