Friend for a Six Line?

I have a 45 gallon reef tank that currently has a chromis, clown fish, two bar gobies, banded coral shrimp and a six line wrasse. The six line was the last fish to be added (A mistake I learned after the fact.) A couple of months ago I put a green clown goby in my tank and the six line chased it around anytime it came out from hiding and eventually the goby just disappeared. I'm guessing it got to be so stressed out that something finished it off and ate it. I would like to add another fish to my tank- does anyone have recommendations for a fish that the wrasse will not pick on, is reef safe and would be ok in a 45 gallon tank. Thanks!