Swimming speeds of stream fish vary from essentially zero to over six meters per second, depending upon species, size, and activity. Three categories of performance are generally recognized: burst (darting) speed: The speed that a fish can maintain for a very short time, generally 5 to 10 seconds, without gross variation in performance. Burst speed is employed for feeding or escape, and represents maximum swimming speed. cruising speed: The speed that a fish can maintain for an extended period of time without fatigue. This implies a lack of stress, and is the maximum speed traveled by undisturbed individuals. Sustained (prolonged) speed: The speed that a fish can maintain for a prolonged period, but which ultimately results in fatigue. At this speed the fish is under some degree of stress.