Alright so after looking though all the fish i have eliminated most due to possible aggression and not being 100% reef safe. I was thinking a reef safe wrasse would be perfect, but it would wipe out your pod population and then getting the mandarin in there would be even harder.
Soooooo my conclusion of the perfect fish for you is.... drumroll..... a jawfish. The blue spotted one is obviously beautiful, but very pricey. The pearly one is actually really beautiful too, I've seen them at my LFS
and under the blue lights they really glow, one would look so great in your tank. They also have a great personality and I believe it would get along with all the fish you currently have. Doesn't swim around much though, I'm going to look them up on youtube i think haha.