I would recommend getting a job at a
lfs, and getting a business degree. The two are completely different.
Learning all you can about fish will not mean you know how to properly run a small business. Business "sense" is one thing, but there is a lot that comes with running a successful business that you will not understand just by having a good business sense.
Conversely, short of veterinary school (which won't prep you as a business owner) you need to get some experience in aquatic life. I doubt that keeping 5 tanks of fish that you like will prep you in everything required to operate a
lfs either.
I defintely think a combination of the two is the only way to go. You can work at the
lfs to pay your way through school.