The peppermints in my tank kept the aiptasia down but ripped the guts out of my tubastrea as well as all the tunicates and cucumbers in my tank. All the filter feeders in the live rock were removed. They also killed a large sebae anemone. I had to rescue an ultra rose BTA from someone else who had peppermint shrimp too. Once the peppermints were gone, the aiptaisa returned with a vengence. There are many dynamics in a large sps tank with a fuge over 100 gallons and lots of cover when excess fish food can keep all the shrimp happy. In tanks with large predators like lobsters and large brittle stars or large crabs, peppermint shrimp may be the only answer that will work. In tanks with specialized feeders and many soft bodied inverts, peppermints more often than not become a predator and are often reported to do what Joshua described. Most of the Centropygy angels and many butterflies eat aiptasia too and sometimes the peppermints get all the credit for it when they didn't do it all. Its easy to train them to eat aiptasia, just feed one in front of them and they will learn their food is in the aiptasia. They'll figure out the rest. If you keep soft bodied inverts, its best done in a separate QT tank. Since they are not a target predator, proceed with care and maybe you will be one of the lucky ones.