The Aqua Medic Trap-pest is an automatic trap for removing undesirable bristle worms, mantis shrimp, crabs or snails from an aquarium. Bristle worms crawl through a funnel into the trap and cannot find their way out while crabs, shrimp and snails pass through a one-way curtain which blocks their exit. The Trap-pest is easily baited using an external bait basket. Trap-pest 5.9" L x 2.7" W x 2.7" H