Funny as this sounds, I have read that fish from the same localities lakes can read each others body language and understand the noises underwater that each other make. They dont understand the "language" of fish from other areas and this can either work in your favor less aggression becuase of misunderstandings or against you fights from misunderstandings. I have read that Ruby Greens are very peaceful and that you need to be really careful who you house them with. Mbunas are considered the pitbulls of the Malawi cichlids. I dont think its a good mix. Labidochromis caruleus spelling? or Labidochromis Acei are considered peaceful for mbunas but they are still mbunas. Also, remember that each fish has its own personality and you may get an aggressive rogue ruby green or a shy mbuna?Good luck Cricket