I know this is an old thread, but I just wanted to post my experience. First of all, my flame angel was a model citizen (or so I thought) for six months before I started noticing my acans all staying closed during the day. They weren't dying or receeding, and they still put out their feeders at night just fine...just not inflating. Within a week of noticing that, I happened to add a new stylophora, and I immediately saw the flame start hitting it.
So I figured that maybe the flame was ****ing off the acans as well, so I put them in my refugium and they opened right up! To test my theory I stuck one of the happy-again, inflated acans back in the main tank, and BAM, he went right at it...so, it was time to remove him from the tank.
I Google'd the issue, found this thread, and made myself a trap...2 days of tank starvation, and a couple of cubes of frozen mysis shrimp later (they float UP in the trap, therefore staying in for a long time), and success! So I figured I'd share my trap with anyone in a similar boat...good luck!
(Oh, and I said "or so I thought" above, because in the days after the flame angel was out, my wellso brain and candy canes puffed up bigger than ever before, and I've noticed more polyps out on my SPS during the day...sneaky little bastard!)
Note rock inside to weight it down, and another on the lid to close the trap when I let off tension on the fishing line running up and over the rim of the tank.
Tada! OH! And I also managed to temporarily trap a blue-throat trigger, flame hawkfish, and yellow tang
