IMO, your tank already has enough (too much really) fish in it. It is generally accepted that tangs require a tank length of 4ft minimum, I can see the yellow doing OK in a smaller tank, but the Orange Shoulder will be very stressed in such a small tank, as it grows. If it were me, I would return the tangs and go with a dwarf angel and then you could add a lawnmower blenny, a bicolor, a midas blenny, a red lipped blenny or one of the many blenny species out there.