your tank is to small for the peacock cichlids, but the dwarfs would work if you keep them in a pair with plenty of cover(they probably won't breed). Another thing to look at would be ram cichlids, although they will eat shrimp, any fish big enough to eat the shrimp will eat the shrimp. so if your dead set on shrimp then stick with tiny fish. even my black skirt tetras eat smaller ghost shrimp lol its not aggression its just fish nature, shrimp are food to fish.