Is this possible? I like both and im deciding on what to put in my 180 Gallon.
Cichlid Forum didn't really give specifics as to what their diets were. I know what Mbunas are but not sure if Tanganyika have the same diet.
I have done this (partly) and its working out, but i would not advise it and its possibly working out for me mostly through a bit of good fortune rather than any great planning or skill on my behalf (although as mentioned below i have spent a lot fo time getting feedback from both experienced Mbuna and Tang keepers)
My 300 litre is about 80-90% Mbuna, but i do have x3 Neolamprologus Tetracanthus (Tangs) and x2 Copadichromis Borleyi (Haps). Up until recently i also had a Pair of Julidochromis (Tangs) breeding like mad in there and successfully raising lots of fry without any particular aggro or damage.
I am not advocating it, if i was to plan a Malawi set-up from scratch now, i would either make it 100% Mbuna or 100% Haps, to make like simpler.
Like others have pointed out, dietary requirements is a key factor in the set-up. My set-up isnt as straight forward as i would like in this department due to the Tangs in there. I've spent many hours on this forum and specialist Malawi forums getting feedback on the dietary regime i have for this set-up.
I was going to move the Neolamprologus Tetracanthus but they have been in there for 6-months plus now and their colouring is awesome and they have never shown any behaviour to suggest they are stressed by the Mbuna
PS - my tap-water pH is somewhere between 7.5 and 8.0 (closer to 8.0 i think) going by tests and when i've done GH and KH tests in the pasts and posted on forums, they have been deemed to be appropriate for both Mbuna and Tangs
I do agree with what CFC and Ferris have said, just wanted to give you my take based on my experience.