I agree with Mike about not mixing Mbuna'a and Peas or Haps. If your looking for a nice purple color check out the Aulonocara Ethelwynnae Chitande's. they are a bluish purple and get more purple as they get older. These guys are a mellow Pea or Old Hap. So housing them with Mbuna's is a bad idea. Also The Chitande species are very unique coloring. They will change from a purple to blue as they swim thru the water. I have 3 of the species and they are nice fish with very unique coloring.
Sorry these are my favorites so I had to vote for them!!