There seems to be a likelihood that the fish has some kind of gill irritation. That could mean a parasite, pathogen, or irritation from water quality.
You've left out important info such as how long you've had this fish, if it was quarantined, the kinds of foods it eats, your system information and water quality measurements. If the fish was eating the right kinds of foods with supplements and additives like recommended here:
http://www.reefcentral.com/forums/showthread.php?s=&threadid=785228
the fish should live for several weeks without eating.
I would check the water quality and even if you can find no reasons for concern, perform a large water change.
Without even a reasonable diagnosis to go by, I'm afraid you're shooting into the dark and hoping to hit a target.
My best guess would be to move the fish into a hospital tank. On its way there, perform a freshwater dip:
http://reefcentral.com/forums/showthread.php?s=&postid=7142933
In the hospital tank, if the FW dip has not improved its condition any, then administer an organophosphate containing medication. That would be like trichlorfon, Clout, Fluke Tabs, or Dylox.
If the fish was suffering from an internal/intestinal parasite, I don't think it would be exhibiting the breathing difficulties nor the flashing symptoms you've mentioned.
Sorry that my opinion is not better.
