A gravid female collected and preserved from Citico Creek had ovaries containing 287 oocytes in three size classes. The occurrence of polyandry in N. baileyi is not clearly documented. Males and females in breeding condition are found together from early June to mid-July. As in other species of Noturus for which life history data exists, following spawning, the male smoky madtom assumes the responsibility of guarding the clutch and keeping the nest cavity free of silt until the larvae leave the nest. While in the capacity of nest-guarder, the male does not feed.
Females attain greater lengths than males.
Sympatric with Noturus baileyi in Citico Creek, at least from creek km 13.8 to 16.6, is the rare and Federally threatened yellowfin madtom, N. flavipinnis. The duskytail darter, like the yellowfin madtom, is known from only three other localities in Tennessee and Virginia. The Little Tennessee River is inundated for most if its lower 100 miles by a series of six dams. It is not known whether these reservoirs have had or continue to have an affect on the Citico Creek population. Tellico reservoir, the lowermost reservoir on the Little Tennessee River, inundates the lower 1.0 km of Citico Creek and may have impacted the species there.