I have a Frontosa colony in a 220 (x11). Their tank mates include Neolamprologus Leleupi (x2), Neolamprologus Brichardi (x6), Synodontis Petricola (x1), Synodontis Eruptus (x2), Altolamprologus Compressiceps Mwela Orange (x2), and BSN Plecos (x5).
I have seen them kept with Peacocks and Haps of equal size. If they are bigger, I have seen them with mbuna as well. I am not sure of the impact after being alone for so long as I got my colony by purchasing 3 groups within a few weeks of each other when 1"-2".