A serpent is on the maybe list, I'll pass on the shrimp as they make target feeding this many corals a challenge.
The open top further restricts fish choices. If anything a couple nano fish such as cardinals or a pair of Picassos and an RBTA (added long after the tank matures.) I created a perfect environment for an Anemone in the center pillar, just not sure I'm willing to give up that much space and deal with the possibility of it going on a "road trip".