In the US it is fairly easy to start your own small business, as long as you don't need funding... You can register your entity as a sole proprietorship for free or have a lawyer draw up documents for a Limited Liability Corp. (LLC). A LLC will cost around $500 to file, but offers some tax advantages and legal protection. When I was running my reef business I ran as a sole prop. and just wrote out reciepts to area businesses. A business plan will help you identify weaknesses in your idea, but if you are growing fish and corals anyway a market analysis to see if your area will support it is pointless. Now a market analysis to identify possible sources of revenue is a whole other game and would be a great time investment. Do not forget to contact wholesalers. Even if they are a few hours away from you a day trip with a couple thousand fish can be worth it.