I actually have 7 leopard wrasse and they do need a deep sandbed. If they cannot bury in the sand they will end up damaging their mouths, etc and will usually not make it.
Make sure that you introduce all of them at the same time. I have 2 blue star in my qt. tried introducing them to the display but got chased around by the leopard wrasse trio(meligris, ornate & black) in the display. I had to catch them and put them back in Qt
