On 11/7/07 I acquired some Favia frags and placed them on the sand of my 65g mixed reef with T5 lighting. They're doing fine, looking good and growing. On 11/20/07 I added some Aussie Acan Lords and a Micromussa. They were initially also on the bottom for a while and then I moved them to about midway in the tank. For several weeks they looked good and I was feeding mysis, brine and cyclopeze. They were what I'd describe as full and fluffy and were adding new heads. One day all the Acan appeared shriveled and they have not recovered. This happened about 3 or 4 weeks ago. I still continue trying to feed, but get little or no response. I moved a couple back to the bottom but there is no change. They still have color but are shrunken. I can't figure out what changed and caused this quick negative response in what appeared to be "happy" corals (acan and micro) that didn't seem to affect the Favia. I also have a Lobo and Mycedium near the bottom which continue to do well. I guess what I'm asking is do the Acan and Favia require such different conditions and if so what? Also, are the Favia just an easier coral to keep? There is a long-nosed yellow butterfly that makes it difficult to target feed, but the only time I've ever seen it picking on corals is when I feed. I can't believe it is the source of the problem since the problem developed in just a day. Thanks for any help offered.