A friend of mine had 2 pair of large festae in a 220, with about a half dozen mbuna as targets. They all grew up together from 2" or so, the males attained around 10"-12", females about half that size.
The pairs would spawn on opposite sides of the tank, and in most cases would live harmoniously, but not always.
He kept another cycled tank at the ready though, and occasionally had to use it.