How large do the WCMM get and do they school well?
I have a Fluval Spec V (just a notch above 5G). After looking at the tank, its clear i'd have to go with some micro rasbora for even a decent schooling fish. I don't know how CPDs do in that respect.
For now, I have pygmy cories also planned for this tank as well as cherry shrimp. We'll see how it goes!