What do you mean some? I have a friend that one that ate his aptasia(good), but also ate his button polyps. How do I lnow which ones to get? Are there different kinds?
allot of places sell camel back shrimp Rhynchocinetes Durbanensis as pep's and they will eat polyps and will not eat aiptasia.
Lysmata wurdemanni are the true Peppermint shrimp and eat aiptasia and do not harm other corals or pick at your feather dusters.
the camel back come from the Pacific and the Peppermint come from the Caribian
hth
kc