dpk2313;3865794; said:
NO demasoni they are a pita once they're over 3"
yellow labs
Nimbochromis
and all kinds of aulonocara peacocks
almost all african cichlids will interbreed with similar fish but its perfectly natural, the fry will more then likely be eaten before it matures if left in the tank though
Demasoni will do very well in a tank that size that is appropriately decorated.
You can certainly keep different mbuna together without creating hybrids. The stock I suggested for example should not produce hybrids. IME - a tank with enough rock work will almost certainly allow some fry to grow and reach maturity.
Peacocks would provide great color - but only for select dominant males. I do think that if this tank is in a business and you really want a tank with a huge splash of color - then a great mbuna stock is the way to go. Also, with a tank this size, you could add male peacocks with the mbuna, even smaller haps like fryeri and borleyi. Large haps like venustus, rostratus, etc would be cool, but would not give you as much color as the mbuna (and would eat dwarf mbuna).
You have gotten a lot of good suggestions. One thing to keep in mind is that the smaller the fish compared to the tank, the less you have to worry about how fish will get along long term. I think you could put sand and a ton of rock work, fill it with mbuna and not worry about the stock for a long time. Just be sure to maintain your water quality.
Wow, amazing tank! 
