The first step is choosing which side of the pond, whether it's africans or south/central american but the different continents should not be mixed due to different aggression and some dietary needs. I personally lean towards the CA/SA guys but I keep and sell African peacocks. So with that in mind i would stock a pair Salvini's, Rainbow's or Honduran Red Points. These would still allow some dithers and bottoms feeders to boot. So research some key words like mbuna, Malawi peacocks, south and central cichlids for some idea's to what you may be looking for. But the last thing some of those southern boys and girls will grow far to large for a 55g. Any questions feel free to ask.