Abstract: A device for modifying the behavior of fish, causing them to swim along a desired path, projects sequences of sound into the water, resulting in sound wave patterns which direct the fish along the desired path. The device includes a fish detector, which detects the monitors the activities of fish, an array of sound projectors and a controller. When fish are detected the controller generates sequences of signals which are applied to the projector array. The projectors project corresponding sounds into the water, producing the sound wave patterns. The detector monitors the activities of the fish and the controller, if necessary, adjusts the sound sequences until the fish are directed along the path. When the detector no longer detects any fish, the controller stops applying signals to the projector array, preventing approaching fish from habituating to the projected sounds.