I have had a dragon wrasse before, in a 125g agressive tank. It was one of my favorite fish, and had lotsa character. I really enjoyed watching the wrasse bury itself to sleep at night. It grew to about 8 inches in total length. They eat voraciously off of live rock, so I would be careful as to what you have in your tank before you get a dragon wrasse.
The one question I have about a dragon wrasse is I have seen green and brown dragon wrasse. What's the difference? ---? species? location? Mine was green, not that it makes any difference.