Maybe it's dependent on the fish. I really like the looks and color of this wrasse. I have 2 other wrasse in the tank, solon and orange-back fairy wrasses, and want to add a carpenter's flasher and the melanurus, but don't want to add a sand bed.
It's just not right... they rely on the sand for their protection and comfort... they require sand to thrive... will they live, maybe but it won't be best for the fish... put a container with sand or a pile of sand in the back... I have a BB and have a section of sand behind the rocks with a small acrylic wall... and I plan on having a melanarus
I do not recommend keeping any genus of wrasse which sleeps in the sand in a BB tank. It does not bode well for their longevity. A sand container is a simple solution for BB tanks.