
In the video, a manually-operated rotating fish trap is installed along the edge of a wooden dock extending over an artificial lake at an amusement park. The device consists of three primary components: a horizontal steel axle mounted 50 cm above the waterline, two fan-shaped steel mesh cages (each approximately 80 cm in diameter) fixed to this axle, and a hand crank connected through a 3:1 gear reduction system. Visitors rotate the cages by turning the crank at 2-4 revolutions per minute.
The submerged lower third of the cages (25-30 cm depth) functions as a scoop. As the cages turn, water flows through the 15-mm mesh while trapping fish longer than 10 cm. Centrifugal force expels 80% of water before the cage segment clears the surface. Caught fish then slide along the cage’s inclined mesh surface into a fiberglass collection trough (120 cm long × 40 cm wide × 25 cm deep) embedded in the dock decking. This trough maintains 10 cm of water depth via drainage holes.
The mechanism employs grade-304 stainless steel for corrosion resistance and has safety features including a finger-guard shield over moving parts and non-slip deck plating. Parks typically stock the lake with fast-breeding species like koi and catfish. Routine maintenance involves monthly bearing lubrication and bi-weekly mesh inspections to prevent algae buildup. The system operates without electricity or baits, providing eco-friendly interaction between visitors and aquatic life.