Mandarins are a beautiful fish, but they don't exactly sift the sand
Besides, I wouldn't recommend trying one unless you have a well established, 55g or greater, 100+lbs of LR and a complete sump/fuge system. And by well established I mean up and running well for over a year or so
But, if your looking for an awsome SS goby with a little color.. try a diamond goby, there sand sifting machines and they look pretty neat too. A buddy has one in with a niger and a porc puff and he still never stops sifting. He has a whole system of burrows under his LR. I would say him, or try a Randals, there a beautiful species as well