N. h. hildebrandi, which inhabits the Homochitto River and Bayou Pierre, has a long head and a mottled coloration.

N.h. lautus lives in the Obion and surrounding rivers; this subspecies has a shorter head and four light-colored oval areas on a red-brown to black back.

[2][4] It is commonly found in shallow areas containing submerged logs, sticks, leaves, and other debris.

[4] The least madtom's spawning season lasts from June through August.

To prepare for spawning, adults take shelter, either singly or in pairs, under stones, shells, or in debris.