You have Aquatic Critter in Nashville. Emerald Bay is a short drive away in Hermitage. 7 Seas in Hendersonville.
Aquatic Critter is a large store with tons of Freshwater, reptiles and saltwater.
Emerald Bay is a very small store with only saltwater and reptiles. It does look like a hole in the wall, but typically has more corals and a better selection of them than any other around here. People there are also wonderful and I have known them for years.
7 seas is all saltwater, smaller store on the backside of the building (only mention this as GPS takes you to the front lol). Decent selection and great group of people.