EVERY reply is the same. many hours at the business, followed by many hours at the business.
Finances. Do you have enough capital to cover the business [ lease, ins, utilities, inventory , payroll, unforeseen issues] for a few years?
You get what you put in to it AND you must prepare yourself, mentally, for every unexpected piece of drama that employees bring [ wife, GF, BF, kids] to the job. When you hire someone, can and will they be able to operate, make decisions,, if and when you are not on site / available?

Is your business seasonal and how do you adjust for said times? Besides selling fish, coral, and all associated items. Are you going to offer seminars / tutorials on maintaining their tanks. Are you going to offer in home maintenance plans, lease a tank to small business (dentist, Dr, etc) for those who might like your product, but not want the hassle of cleaning , and upkeep.