Hey 1slapnuts, I'm really new to this (and I know this is better off on a different board), but I read somewhere that an octopus will clear out the mantis shrimp in no time. It will eat many of the other animals you put in too, so you have to "borrow" it to clean your tank of undesirables, and then give it back. Anybody hear of this? Can't remember where I read it...perhaps Sprung.