In your particular case, Jaguar, I'd go with the advice of hitillidie and try the melanurus wrasse first because they tend to be quite peaceful. As you probably already know, YTB damsels and six-line wrasses can become pretty mean sometimes. Yellow coris wrasses usually are peaceful. Don't see the yellow coris wrasse being any sort of problem if the tank only contains a pair of fang blennies. Probably wouldn't ever add a yellow coris wrasse to a tank containing jawfish, though, because of the wrasses constant sand surfing.