Living fish counting appts. for use in fish culture - uses opto-electronic detectors on either side of shallow, flat-bottomed channel to detect passage of fish and drive electronic counter

摘要

The counter has detectors placed in a flattened duct connecting an upper basin to a lower basin, and has the bottom of the duct raised so that the level of water passing over it is low. The fish passing through the duct are spread in a single layer over the opto-electronic counters distributed over the duct area. The opto-electronic detectors consist of an emitter and receiver pair, which are coupled when there is no fish present and decoupled when a passing fish obscures the light. The detectors drive an electronic counter which continuously updates and displays the count of fish passing the detectors.