What do you plan on selling/providing?
As long as your overhead is low, then yea. I would test a facebook page (I.E Calhoun Fish Store) and see how many hits you get for corals, service and the like. How many people do you know and how prominent are you in the community?
Probably have better luck maintaining a giant reef tank and selling the corals on R2R or ebay. Most stores make their money through maintenance and probably water.
Most everything can be bought online now, even corals. However, most people go for the experience and probably to see the true condition of the fish/coral for issues.
Can get online - rodi, salt, chemicals, food, tools, equipment, live rock, corals, fish.
In store - experience, supporting your local economy, wysiwyg, tribal knowledge, service/guidance, sell your frag/corals to them, bumping into other people in the hobby. If your customer has a wife and/or kids it's about the experience and options. You get to see new things you want firsthand.
Depends on if you are for profitability or pleasure. That goes for any business though, in this case perishable goods.