Fish
Margined Madtom
Noturus insignis · also called margined madtoms
Beneath a flat rock in a clean Atlantic slope stream, a margined madtom waits out the daylight hours, the dark border along its fins barely visible in the shadows until it finally emerges after dark to forage across the gravel bottom.
Overview
The margined madtom, Noturus insignis, is a small catfish native to clean streams and small rivers across a broad range of the eastern United States, particularly along the Atlantic slope. Its distinctive dark-edged fins and mildly venomous spines make it one of the more recognisable small madtom catfish in eastern North American streams.
A small fish with a clear warning label
The margined madtom’s dark-bordered fins double as a subtle warning that matches its actual defence, a mild but genuinely irritating sting that gives this otherwise unassuming small catfish more bite than its modest size would suggest.
Status
Least Concern — widespread and stable across suitable clean stream habitat throughout the eastern United States.
Margined Madtom: common questions
Why is it called the margined madtom?
A margined madtom displays a dark border along the edges of its dorsal, adipose, and caudal fins, a distinctive pattern that gave the species its common name and helps distinguish it from other similarly shaped small madtom catfish.
Can a margined madtom sting you?
Yes, the margined madtom has venom glands at the base of its pectoral and dorsal spines, capable of delivering a mild but genuinely irritating sting if the fish is handled carelessly, a defensive trait shared broadly among madtom catfish species.
When is the margined madtom active?
A margined madtom shelters beneath rocks, logs, and other debris during the day, becoming active mainly at night to forage for aquatic insects and other small invertebrates.
Where does the margined madtom live?
The margined madtom is native to clean streams and small rivers across a broad range of the eastern United States, particularly along the Atlantic slope, generally favouring a rocky or gravel bottom.