We observed a large adult Paddlefish entrained from the Mississippi River through the Bonnet Carré spillway, south Louisiana, which was injured and underweight. We captured, measured (23 metrics), and tagged the fish. After it had spent a week at large on the floodway, we recaptured and released it back into the Mississippi River. The specimen was re-captured eight months later in northern Mississippi, 627 km upriver from where it was released. Distance traveled and water velocities in the river indicate that the fish was traveling at least 90–197 cm/s for prolonged periods, equivalent to gross speeds of 77–170 km/d. This incident suggests that a large entrained fish, trapped for several days in a hyperthermic and hypoxic habitat, can be viable when returned to the river. It also demonstrated that rescue efforts could reduce impacts of spillway operations to fish populations, and that comprehensive field assessment of fish morphology can be benign t o fish.