The lateral band varies from distinct to faint among fish from different populations. The small, sub-terminal mouth is slightly oblique and no barbel is present. Hooked pharyngeal teeth on slender arches are found in an array of 4-4. Mimic shiners have dark pigment around the vent and base of the anal fin, which is absent or faint in the bigmouth and sand shiners. This shiner has a poorly developed or absent mid-dorsal stripe.
Infraorbital canals are complete in the mimic shiner but interrupted in the ghost shiner.
Dorsal and anal fins contain 8 rays and are rounded in shape, as opposed to falcate-like in the ghost shiner. Pectoral fins contain from 12 to 15 rays, and the pelvic fins contain 9 rays. A complete, elevated lateral line has 33 to 38 scales with a spot above and below each pore. Northern mimic shiners have between 35 and 38 lateral line scales, which are almost 3 times as high as wide. Mimic shiners inhabit riverine habitats with moderate to swift current over sand bars or spoil banks.