What's to misunderstand about 6 line wrasses? They often turn into pescacidal maniacs as they mature and are often a poor choice for community tanks. With a 180 gallon tank a 6 line would be a pretty poor choice given the option for Halichoeres Wrasses that are much better tank mates in general. Yellow Wrasse, Melanurus Wrasse, Christmas Wrasse (specifically H.Claudia), Red Lined Wrasse, Richmond's Wrasse would all be much more visible in a tank of that size and provide similar pest removal services.