We've got a 150gal reef, and in getting started transferred all the inhabitants from my fish only tank into the reef. Very shortly after realized my mistake. In response to getting these "mistakes" out of a reef, here's some information that may help....
I've tried everything from buying "The Trap" by UltraLife Reef for $45.99 ... NOT! Waiting patiently with a net for hours for a fish to wander by.... Fishing hooks with bait.... Nothing worked.
At my LFS, I ran into a brilliant guy who let me in on a little secret. Fish can't see the color RED. So here's what you do. Go a couple of days so the fish are real hungry. Wait for night. Prepare fish food. Add it to the front of the tank with all the pumps off so the food stays at the front. When the fish start on their feeding frenzy shut off every light in the house (inside and out). Its gotta be pitch black. Then turn on a red light. Flashlight with a red filter in front works fine too. You'll be able to see the fish, and they wont be able to see you. You'll be able to net out the target fish. Always start the net low, and come up from under the fish.
I've had very good luck with this method, to date pulled out a Trigger, two Tomato Clowns, a puffer, 3 brittle stars, and other assorted little guys that should never have been added to my reef.
Good luck and hope this works for you...