New to the Forum - Need advice on adding fish

Hey everyone!
Just set up my first fish tank about a month ago and loving it. I currently have a 65g tank with a 55g hanging filter and a 20g hanging filter on it. I don't have as much rock cover and cave landscape as I would like but I plan on remedying that tommorrow. I wanted your thoughts on what will play nice with the current inhabitants of my tank and how many fish I should put in.

Current Inhabitants:

1x Metriaclima Livingstonii (Livingston)
1x Metriaclima pyrsonotos (Red top Zebra)
1x Metriaclima esterae (A male red zebra who is actually pink)
1x Pseudotropheus crabro (Bumblebee)

1x An unknown peacock which I believe may be a (Sunshine Peacock) Aulonocara "Stuartgranti Maleri" but I'm not really sure on that one.

1x Black Fin Shark

They are all very young and around 1-1/2 to 2 inches. The peacock is low man on the totem pole however he seems to be doing okay. Everyone seems to be holding their own with the Red Zebra a strong dominant figure. I don't know the sexes of any except the Red Zebra who is a male. Any advice or ideas on additional species or amount of fish would be greatly appreciated.

I'll post some pics later.