I added a royal flasher to my display ~4 weeks ago. He's feeding very well (and did all the way through QT) however there seems to be some aggression issues from the other inhabitants. The first week or so I observed some chasing from my female clown (who is about the same length as the wrasse but much more bulky) but there didn't ever seem to be any contact. After that everything seemed to settle down and there was none or very little chasing. The last week or so however the wrasse has been missing progressively more of his tail fin, to the point that today some of it is almost completely gone. The last two days I've noticed my banggai cardinal chasing him occasionally but again no actual contact. The fin doesn't look ragged or infected as far as I can tell so I think it is nipping as opposed to fin rot. Today while still feeding well he has spent a lot of time sulking in a corner - sometimes actually laying on the sand bed wedged up against the back glass. If I can work out who the culprit is I can move it to my QT for a couple of weeks timeout, is this likely to solve the problem? Is there anything else I can do to stop the aggression/is it likely to stop eventually without me intervening? I'm not even 100% sure if it's a fish - I've never seen any actual nipping so it could even be a hitchhiker crab? Tank specs: Reefer 250 2x Common clowns 1 Banggai cardinal 1 Peppermint shrimp (do they ever nip fish? I think the flasher sleeps in the same area the peppermint lives in) 4x hermits Assorted snails Thanks!