i would stay with either a few banded shrimp and corals, or maybe 2 skunk cleaner shrimp or 2 red fire shrimp, just to catch the eye plus your corals, maybe you could get away with a pigmy wrasse or a small goby
Coral banded shrimp will fight to the death unless it's a mated pair. Even in my 210 the male and female fought to the death within a month. Some Coral Banded Shrimp tend to get aggressive toward others that invade their space so I'd stick with some cleaners or blood fire shrimp instead.