Took a while but finally caught the mantis shrimp in my display tank. I've lost a couple of fish to him. Found his little hole that he loves to hunt from and plugged both ends with blue tac. Removed the rock and flushed it with sparkling water. Came straight out. Grabbed him with pair of plastic tongues which he struck a couple of times with a loud crack. Glad it wasn't my finger. The pic isn't the best. Probably 2-3 inches in length. Hopefully no more clicking in the tank.