Colorado squawfishPtychocheilus luciusspawned in widely separated areas throughout the 350-km section of the upper Colorado River upstream from Lake Powell, Utah, as evidenced by the movement of radio-tagged adults during the spawning season and the later capture of larvae. With one exception, tagged fish remained separated from each other during the spawning season. Distances moved by tagged fish were not related to fish size or location of initial capture along the river. Movements were generally shorter (mean, 23.2 km) than those reported for this species in the Green River basin, in part because of important habitat differences between the two rivers. Most tagged Colorado River fish were found near their initial point of capture after the spawning season.