Pygmy Madtom

The pygmy madtom has an extremely limited distribution, appearing only in samples taken from the Duck River, in Humphreys and Hickman Counties, Tennessee; and from the Clinch River, Hancock County, Tennessee. These two locations are separated by about 600 river miles, though no current evidence indicates the entire historical range of the species.

The pygmy madtom is the smallest of madtoms, reaching only about 50 mm in length at adulthood. It is dark brown dorsally and nearly white ventrally, and is similar to the least madtom, but is distinguished by its white snout and large teeth on the front edge of the pectoral spine. The caudal fin has a dark band or dusky blotches in the middle. The anal fin has 14–17 rays. N. stanauli has currently been observed and collected in moderate to swift gravel runs of clear medium-sized rivers in pea-sized gravel of fine sand substrates. Although no observations of seasonal habitat shifts have been made, the closely related smoky madtom is known to switch from riffles to overwinter in shallow pools. Two closely related species, N. baileyi (smoky madtom) and N. flavipinnis (yellowfin madtom), are found in the flowing portions of pools during the reproductive season. Many specific biological traits of this madtom have not been gathered to date, mainly stemming from a lack of observable specimens in their natural environment. A total of 10 individuals have been found from both locations since the species was listed as endangered in 1993. Conservation Fisheries, Inc. of Knoxville, Tennessee, was able to propagate young on several instances and reported adult activity was limited only to the early evening hours. …