In a tank that deep (and assuming you have a sand bed) it might be cool to keep a few Yellow Headed Jawfish. Also considering the depth, seahorses (if you have a chiller or very cold fish room). And while you are at the cold water tank, thow in a Catalina Goby.
Otherwise all of the usual nano suspects need apply. Cryptic Wrasse (Pink Streaked) is one of my favorite dwarf wrasses. Flameback angel. Dwarf lion, maybeeeee.
Of course now is when you are going to tell me you are hosting super delicate SPSs exclusively in that tank.