There's actually a lot of material out there on raising fry, the 2 biggest problems are filtration systems, and feeding them. In theory, if you had a regular supply of green seawater, fresh from the ocean and kept them in a tank (kessel) running on just an air stone, you could raise them up, but in practice its not practical. I guess the other idea, in theory is if you were to have a fish cage, and placed the fry in the ocean, they would also develop, assuming the cage had some method of holding them. Anyway, I if you had a giant container of green sea water sitting outside in the sun, you may be surprised what you catch in a few weeks. As for me, I tried raising sexy shrimp larval in a kessel, but couldn't get them past 10 days.