I wish I would have been here and you would have posted recos before you put that POS Damsel in your tank. I've had most every Damnsel avaliable to the Hobbyist - one point. IME THe Black Domino is hands down the worse. I honestly don't know why any experienced Hobbyist would want one as they're ultimately a pain in the ass, as your experiencing and they're nothing special to look -.
A good friend had to take apart his entire(gorgeous) Reef as his Black Domino damsel was reaking havoc. He Tried everything.....*red light method*, Adding a Small Lion......nada worked on that crazy lil
[hr]
. He finally had to take his entire 155gal. reef apart over 1 lil pos Damsel. Then he flushed the Poor think down the Toilet(ooh the Lack of Ethics..hehe).
The problem is that many people initally add Damsels to their relatively new tanks to find that they can be more heartache then they're worth once the tank is truly established.
Good Luck cathing him. It might sound Crazy, but relative to your setup, the Lionfish addition(like Jer is saying) might not be so bad if all else fails. Try the*redlight* method that should be avaliable here via the Serach funtion.
If you didn't live in Oz, I'd be happy to(try to) Catch him for ya with Minimum problems so I can feed his crazy ass to my buddies Eel. Throw him back in the Ocean.
Peace