Unfortunately, Aquatic Critter is the only one I would recommend. Fins of Franklin is still open I believe, but the last time I was there they appeared to be on the verge of closing.
Emerald Bay is in Madison. When they were in Bellevue, I used to go in frequently, but all of their tanks had various issues you don't want in your tank.
On Aquatic Critter, their fish tanks appear pristine, but I don't buy any coral from them. Their coral tanks have aiptasia and various forms of algae I don't want in my tanks. It sort of sucks to live in the Nashville area and have a reef tank, there is nothing to choose from.
I am just going with Live Aquaria and Divers Den.