Slender madtom (Noturus exilis)

Slender madtom in habitat
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Slender madtom fact file

Slender madtom description

GenusNoturus (1)

A member of the catfish family, the slender madtom (Noturus exilis) has a flattened head and a long, slender body (2). The snout is blunt, with two short, feeler-like barbels which point upwards from the nostrils, and a further four white barbels which protrude from the underside of the chin (3) (4). The slender madtom is typically yellowish-brown to grey-black on the back and sides, sometimes with faint yellowish blotches. The underside is pale yellow, becoming duskier in older fish (2) (4) (5). There may also be a light yellow area around the eyes (4).

Length: 7.6 - 15.2 cm (2)

Slender madtom biology

The slender madtom feeds primarily on aquatic insects and their larvae, as well as small crustaceans (2) (6). Most activity occurs at night, with feeding generally peaking around dawn and dusk. During the day, the slender madtom shelters under rocks or other cover (2).

This species spawns between June and July. The female produces 20 to 150 eggs, which are laid in nest cavities excavated by the male. The nests are usually found under large, flat rocks in shallow pools with little or no current, although some nests may be placed in shallow riffles. The male slender madtom cares for the eggs, with the female leaving the nest soon after spawning (2) (4).


Slender madtom range

Found only in the United States, the slender madtom inhabits the Green, Cumberland and Tennessee River drainages in Kentucky, Tennessee and Alabama. It is also found in the upper Mississippi River basin from southern Wisconsin and southern Minnesota to the Ozark and Ouachita Highlands of Arkansas, Kansas, and Oklahoma (5) (6) (7).


Slender madtom habitat

The slender madtom inhabits small- to medium-sized streams with clear water and rock or gravel bottoms. It is most common in rocky riffles and small pools of flowing water (2) (5) (6).


Slender madtom status

The slender madtom is classified as Least Concern (LC) on the IUCN Red List (1).

IUCN Red List species status – Least Concern


Slender madtom threats

The primary threat to the slender madtom is degradation of its stream habitat. This is often a result of agricultural runoff, erosion of stream banks, and the alteration of river flow due to damming (4).


Slender madtom conservation

There are currently no known conservation measures in place for the slender madtrom. A status survey should be carried out to determine the extent of this species’ range, and further study is needed into its natural history (2).

Recommended conservation measures for the slender madtom include monitoring water quality and habitat alteration in streams inhabited by this species (2).


Find out more

Find out more about the slender madtom:



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Adipose fin
In some fish, a second dorsal fin consisting of a flap of fatty tissue, which lacks supporting rays.
Anal fin
In fish, an unpaired fin on the under surface of the fish, behind the anus.
Fleshy projections near the mouth of some aquatic vertebrates.
Caudal fin
The tail fin of a fish.the tail fin of a fish.
Diverse group of animals with jointed limbs and a hard external skeleton, characterised by the possession of two pairs of antennae, one pair of mandibles (mouthparts used for handling and processing food) and two pairs of maxillae (appendages used in eating, which are located behind the mandibles). Includes crabs, lobsters, shrimps, woodlice and barnacles.
Dorsal fin
The unpaired fin found on the back of the body of fish, or the raised structure on the back of most cetaceans (whales, dolphins and porpoises).
The stage in an animal’s lifecycle after it hatches from the egg. Larvae are typically very different in appearance to adults; they are able to feed and move around but usually are unable to reproduce.
Light rapids where water flows across a shallow section of river.
The production or depositing of eggs in water.


  1. IUCN Red List (August, 2013)
  2. Mississippi Museum of Natural Science (2001) Endangered Species of Mississippi. Mississippi Museum of Natural Science, Mississippi. Available at:
  3. Wisconsin Department of Natural Resources - Slender madtom (July, 2011)
  4. Ross, S.T. and Brenneman, W.M. (2002) The Inland Fishes of Mississippi. University Press of Mississippi, Mississippi. 
  5. Florida Museum of Natural History - Slender madtom (July, 2011)
  6. FishBase - Slender madtom (July, 2011)
  7. USGS Nonindigenous Aquatic Species - Noturus exilis (July, 2011)

Image credit

Slender madtom in habitat  
Slender madtom in habitat

© Marshal Hedin

Marshal Hedin


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