Unless you have unlimited $$$$$ where opening an LFS would be more of a hobby than a money-making endeavor, you had better seriously consider all costs. All the LFSs in my area have closed down, with the exception of one. The owner worked there 7 days a week, and the shop was closed only when he had to pick up fish. He couldn't afford to hire help. He could not take vacations. After struggling for a long time, he finally sold out. The place now seems to be run by a family who have branched into hamsters, birds and snakes. The fish section is minimal. I've never seen any customers in there when I've gone in to check things out.
Even if you had the money to buy all the stock and setup equipment, you need to figure out what your monthly expenses will be, including your salary and restocking. Then figure out what you need to make in sales every day to meet your costs.
With todays economy, starting any business has a lot of risks. Starting an LFS is just risky business. It seems to me, that LFSs make most of their money selling fish keeping products, not so much by selling fish. As a fish keeper, I never think, "I'm going to buy this marked up item from the LFS to support him and keep him in business". When I need something, I go online and buy from the vendor with the best (lowest) price. The bottom line is that LFSs cannot compete with big online vendors. LFSs probably make the most money off newbie fish keepers, selling them complete set ups. How many of us would order a 300 gallon tank through an LFS? If an established fish keeper has excellent water parameters in his/her tank, how often are their fishing dying and needing replacement? How often are they buying new tanks and needing more fish? I personally like to check out fish, but I'm not interested in buying any.
As the economy worsens, discretionary spending will decrease. Fish keepers will down size, not expand. If a person has unlimited resources and can keep dumping his money into his LFS (as a hobby), it could be a lot of fun. If a person needs to earn a living from his LFS business, it would probably be a nightmarish headache.