Thirty-three miles west-southwest of John's Pass, in a part of the Gulf of Mexico where the water is more than 100 feet deep, a Madeira Beach company wants to start a farm. The crop: fish. The company's plan calls for raising thousands of cobia, amberjack and other species in conical net cages anchored to the sandy bottom. Once the fish are big enough, they would be sold to seafood companies. If Florida Offshore Aquaculture gets federal permits for a two-year experiment, the company's founders will establish the first fish farm ever attempted off Florida's coast, and one of the first...