Oh I agree, not something I would do either. But it would be a way to put more bang for the buck into the footprint, as it were. Westies are a good option, if you don't mind mixing fish from different areas. In addition to the Nanochromis, there are smaller Pelvicachromis that would work like taeniatus and subocellatus, or the close cousin I am currently keeping, Enigmatochromis lucanusi which was formally known and still sold as Pelvicachromis sp. bluefin.