Trap-pest is an automatic trap for removing undesirable bristle worms, crabs or snails from an aquarium. Bristle worms crawl through a funnel into the trap and cannot find their way out whilst crabs and snails pass through a one way curtain which blocks their return path. The Trap-pest is simply baited from the outside. Dimensions L 15.5 x W 7.5 x H 8.5cm.