Longitudinal variations in power production by red muscle during steady swimming in fishes have stimulated debate on how fish power swimming. In this study, kinematics data (tailbeat frequency, muscle length change, and EMG phase and duty cycle) were collected from three positions on rainbow trout, Oncorhynchus mykiss, swimming steadily at 10oC. This data could then be compared to kinematics previously reported for largemouth bass, Micropterus salmoides (at 20oC). Further, both data sets could then be used in workloop experiments to evaluate how each species powers steady swimming. At their maximum steady swimming speeds, trout and bass have similar tailbeat frequencies and muscle length change patterns, despite the difference in temperature. However, both EMG phase and duty cycle differ between the two species at all longitudinal positions. The onset of EMG activity occurs earlier and the EMG duty cycle is shorter during each oscillatory length change cycle at each position of swimming trout. These variations translate into different patterns of power production during swimming, because the anterior muscle in trout operates under more favorable conditions in vivo than in bass. Therefore, while bass generate the majority of power for swimming with their posterior musculature, trout generate power along their entire length.