The Topeka shiner (Notropis topeka) is imperiled by extensive changes in stream hydrology. Responses of shiners to changes or variation in stream hydraulics, however, have not been quantified, hampering conservation efforts. We quantified swimming endurance and behavior for Topeka shiners in a laboratory swim tunnel. Sustained swimming (>200 min) was observed at water velocities of 30–40 cm/s. Prolonged and burst swimming (approximately 10 min to less than 0.1 min) was observed at water velocities of 40–75 cm/s and endurance was negatively correlated with water velocity. Larger individuals (4.4–5.5 cm standard length) exhibited greater sustained swimming ability than smaller individuals (3.0–4.2 cm standard length). Oral grasping of wire mesh within the swim tunnel was frequently employed at moderate water velocities (35–50 cm/s); this behavior may limit downstream displacement of shiners during freshets. Topeka shiners are capable of swimming speeds faster than water velocities which they typically inhabit. Fishways and culverts, therefore, may be employed to facilitate dispersal and recolonization. Swimming endurance data are used to determine optimal size and water velocities for such structures.