I had brichardi breed in a 65 gallon tank with kenyi and socolofi. I later moved them into a 35 gallon of their own and their colony flourished, but they weren't exactly languishing before that. It might not be recommended to mix them, but brichardi are tough and mbuna are usually most interested in messing with their own kind. You might need to keep diet in mind, though. Most mbuna would want more vegetable matter in their diet, while brichardi would want more of a carnivore blend. Of course, you could get around this by offering plants, algae, sinking spirulina, and spinach leaf to the mbuna as a complement to a more fish-heavy general flake. The occasional mysis shrimp feast would benefit everyone, too.