My pleco has a spot under some wood that my RBP's like to hang out in, but when he wants that space he chases them out, and he's smaller than them. He's been doing that for several months. I've also had several crayfish, but I've got a crazy one of those now. The ones I've had before have been semi-shy, but last night I dropped in one of the giant goldfish from Petsmart and the crayfish jumped off the bottom and grabbed it. He picked at it for a while, and never let go until the P's got excited enough to take it away from him.