PetSmart - Gulfport, MS
PetSmart - Crossroads Plaza, Intersection of Hwy 49 and Interstate 10, Gulfport, MS
The only reason I mention this mass-franchise pet store is because the plant and fish selection is by far the best in the region. I'd have to drive 70 miles to Covington, LA to find a store with a better selection of healthy plants at good prices.
Their plant section is a three-tiered open top acrylic display with three hanging Metal Halide pendants and pressurized CO2 supplementation. They even get in the occasional beautiful Discus that they keep in the plant display.
The rest of their fish are not the typical mass-merchant fish store you'd expect. Tanks are clean with few/no dead fish lying around. They've got the unbeatable 14 day gaurantee but I've never had to take them up on it.