Nothonotus microlepidum, the smallscale darter, is a species of darter endemic to the southeastern United States. It occurs in the lower Cumberland River drainage in the states of Kentucky and Tennessee. It inhabits shallow riffles with gravel substrates in small rivers. Breeding habits of the smallscale darter are typical of the E. maculatum group in that females deposit large masses of eggs on the undersides of rocks to be protected by the males.