Pokey, some people have had tremendous success without any problems
mixing frontosas' or other lake tanganyikan cichlids with Malawi
cichlids, & other type fish. But most cichlid collectors will separate
the two. ( It's what I do). Books, etc. will say keep frontosa with
other "mellow" cichlids, but in my experiences, I havn't any problems.
But in fairness, I've only housed Fronts with Cy. Moori (blue dolphin),
Victorian Obliques (semi-aggressive), and some Mbuna...