Hmmm..... well, location, location, location.
Also, market research.
You'll need to register a company name.
Find some funding. Venture Capitalists, angel investors, grants, etc.
Buy some land.
Build the facilities.
Get some marketing and advertising going.
Hire a few specialists.
Gain revenue.
Pay off investors.
Gain the rest of the revenue
Make sure you take care of your expenses of maintaining the fish and facilities, pay your employees, etc.
Have fun.
Just a basic business plan if anyone here wants to get serious about the idea. 'Cause I can tell you now, that's the basic outline of any business venture right there.
Good luck to whoever goes for it.