I haven't had any aggression problems with my peppermint shrimp or my coral banded shrimp. I have electric blue legged hermits, too (like suggested below) and they fight each other a lot. 2 ganged up and killed the other one! Dwarf red-legged hermits cause fewer problems and get the cleanup duties done. In terms of shrimp, peppermints are good. I think cleaner shrimp are even better. The coral banded shrimp is attractive, but kind of boring and grumpy, compared to the curious peps.
55 gallon reef tank. AquaticLife 4-bulb T5 HO with 4 LED moonlights. Reef Octopus BH-1000 HOB protein skimmer. TLF Phosban Reactor 150 running 400ml of NPX Bioplastics with a Maxi-Jet 1100 and a BRS Reactor running activated carbon with a Maxi-Jet 900. Vortech MP10w.