I'm assuming you are referring to either neolamprologus multifasciatus, brevis, or ocellatus, as they are the most commonly seen shellie species in the trade. As for a "clean up crew", good luck. My multies kill everything i try, other than a couple nerite snails. I tried a bristlenose pleco baby and they killed it slowly, and they won't let ghost shrimp stay anywhere other than hiding in a patch of java moss or on top of the heater. Shellies are highly territorial, especially when protecting fry. Snails are gonna be your best bet in my own personal opinion, a mixture of 1-2 nerites per 5 gallons, and several malaysian trumpets to help aerate the sand