cleanup as in what sense? some snail can tolerate saltwater, so I bet that there are some that will live in BW tanks. I beleve that the following are also suitable for a BW enviroment. Black Fin Shark, Freshwater Flounder,and knight gobys. thase might be somthing you are interested in. just define what you want it to do, and you will make it easier for us the get you a little clearer answer. hth ~corey