Noturus exilis, also called the slender madtom, is a species of the catfish family Ictaluridae. Ictaluridae includes bullheads, madtoms, channel catfish, and blue catfish. Noturus exilis is found in the central portion of the Mississippi River basin, but is most abundant in Ozarkian streams. Slender madtoms occur west of the Mississippi River in the Ozarks of Oklahoma, Arkansas, and Missouri north to southern Wisconsin and Minnesota. It also occurs east of the Mississippi River in the uplands of Alabama, Tennessee, and Kentucky in the Tennessee, Cumberland, and Green drainages. Edward Nelson first described Noturus exilis in 1876. The slender madtom is moderately large with a terminal to sub-terminal mouth, flat head, small eyes, and black marginal bands on the median fins. Most slender madtoms are less than 90 millimetres (3.5 in). Noturus flavus and Noturus nocturnus are rather similar in shape and coloration to Norturus exilis. Slender madtoms inhabit small to medium-sized streams, in riffle and flowing pool habitats with coarse gravel to slab rock substrates. The presence of a shelter object, such as a large rock, seems to be important in habitat selection.

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