u shouldnt really mix africans with other fish especially mbuna...im not sure of the water parameters a bala shark needs, but i can tell u that a bala shark will outgrow that tank, also bala sharks need to be kept in groups bc they are a schoaling fish
so to have like 4 bala sharks in a 55 would be ok until they grew up to over 10 inches long each, and then with some cichlids in there it would be a crowded tank
