I went thru this before, added two bluefin damsels to my 60 gal bowfront. It was just after first cycle and they were very colorful especially with the blues, and since they are hardy i figured id start with them to get the tank going, (after first cycle i might add, i cycled strictly with liverock) All was sort of well, there was one mean one and one nice one, the nice would never chase the mean. After a few weeks went by i felt confident enough to add some more fish to the tank, this time the fish of choice being firefish goby (dartfish) Three of them. as soon as i acclimated to tank params, i put them in their new home. The mean damsel instantly swam to them and started backing into them, pushing them into the rocks, i watched in horror as one firefish had his back fin ripped off, so i did what my research told me and put a "bottle trap" in my tank, nope the damsels would rather die of starvation then go near the bottle, and after a few days of trying, i decided starving my tank inhabitants to entice just one, was not fair, there was only one other option, take down my aquascape and get him manually. The nice damsel died in the process and the firefish that was injured did not survive. Let me tell you, even with no rock in your tank it is near impossible to remove a devilfish like the damsel, after i got him out, i GAVE him back to the lfs, shaking my head at the man who told me they wouldnt fight. Since then ive researched everything i could about anything i add to my tank, here i am three months later, and peace has reigned supreme since the damsel episode (and my lfs now warns me with every fish that they may be aggressive, as if ill ever listen to his advice again, i know the difference now) damsels are not reef safe. not in my opinion