Berghia did well for me they were very cryptic, only out at night, I only saw a few get picked off, it took months for them to make a dent. I got an aiptasia eating filefish and he did in one week what it took the berghia 6 months to do. I had no luck with peppermint shrimp. As said previously they usually come back because they get in the overflows, sump, etc, etc. Good luck.