Breed me some clown loach, i'll buy everything you raise, guaranteed. If you can breed them darn things you can breed anything.
Joking aside. Some fish are that easy to breed they'll breed whether you want them too or not, unfortunately I don't think you'd have people fighting each other to buy these type of fish from you.
You'd need to concentrate on a few oddball breeds that are:
a) much sought after by hobbyists, giving you a ready market.
b) difficult to breed so you know that said market isn't being over run.
c) expensive to buy so you're really maximising your earning potential.
The clown loach example I gave in jest is possibly the wholly grail of fish breeding. Everybody wants clown loach, especially 5" plus specimens, they're virtually impossible to breed in captivity and they absolutely cost a fortune, even for tiny specimens.
Personally my advice to you though, taking into consideration you're so young, would be just to enjoy the hobby and get some years of experience under your belt before you take the leap into breeding the types of fish you'd need to breed to sustain a business.