Slender madtom  (Noturus exilis)

The slender madtom has not yet been classified by the IUCN.

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).

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).

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).

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).

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).

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 about the slender madtom:

• Wisconsin Department of Natural Resources - Slender madtom (Noturus exilis):
  http://dnr.wi.gov/ORG/LAND/ER/biodiversity/index.asp?mode=info&Grp=13&SpecCode=AFCKA02250
• Mississippi Museum of Natural Science (2001) Endangered Species of Mississippi. Mississippi Museum of Natural Science, Mississippi. Available at:
  http://museum.mdwfp.com/downloads/science/endangered_species_packet.pdf
• FishBase:
  http://www.fishbase.org/summary/Noturus-exilis.html