As long as you you don't put overly aggressive fish with more docile fish it might work out -- but there are no guarantees. Breeding Tanganyikans are super-aggresive. Watch them closely. Also keep in mind that water parameters of the two lakes are somewhat different. To keep things simple choose species from one lake or the other. In my opinion, it also looks better to have a tank that displays fish of similar origins.
Check my sig and see that I have fish from both lake tang and malawi, it's been good so far, but I can't tell the result on the long run....I have both mbuna and peacocks on the same tank....
Hi, I have a mainly malawi tank, I have 1 tang which is a 5 bar cichlid and he gets on fine with them, I also have a pair of victorian cichlids in there and they have bred once. I have had no problems, but you never can tell what they might do