So far my Threadfin has had 0 interest in the hammer I have in the tank. Unfortunately, he also has had 0 interest in the Aptasia, forcing me to buy a file fish. When he gets out of QT we'll see if hammer is back on the menu boys... My yellow tang, now deceased bicolor angel and the threadfin were all best of buds except for the occasional tiff..The threadfin wasn't afraid to show his spikes and charge.. I've got everyone crunched in my 90gal and everything is fine so far... I would like to add a few more corals as test victims... Thanks for this thread as I have been very interested in keeping butterflies with some tangs I have planned for a bigger tank...