(Science: marine biology) swimming speeds of stream fish vary from essentially zero to over six metres per second, depending upon species, size, and activity. Three categories of performance are generally recognised:
1. 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.
2. 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.
3. 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.