Those will all be too big for a 50 gallon. You could add a one from the Lunatus group as they stay relatively smaller. checking out this thread will help.Out of the 3, lineatus, rhomboid and labouti, what would be the best for a 50 gal cube?
Cirrhilabrus Complexes: Inferiority Need Not Apply (1st Revision)
Cirrhilabrus, the “Fairy Wrasses”, are one of the most elegant, active, and colorful reef fish. Their appeal in a reef tank is common to many, but not all have a well-rounded understanding of the compatibility amongst them. Enter the notion of “complexes”: groupings of very closely related...
www.reef2reef.com