The Aquarium Center is the best store of this genre that I've ever been to. They stock all of the popular common fish and aquatic creatures plus tons of ones you won't find anywhere else. The tanks are well cared for and the fish look very healthy. They also carry pretty much everything you need in the way of supplies and equipment and there are a bunch of beautiful display tanks to ogle. The staff is knowledgeable and helpful. The tank room is extremely warm and humid so dress lightly if you plan to spend much time in there.
more