The background: Overfishing is depleting wild ocean fish stocks and threatening the $158 billion commercial fishing industry.

The solution: Hawaii startup Kona Blue is pioneering deepwater aquaculture to farm ocean fish. Although many companies grow freshwater tilapia and catfish, few have succeeded in farming flavorful deep-sea fish like yellowtail tuna and swordfish. Privately held Kona Blue raises a yellowtail-like fish off the coast of the Big Island of Hawaii - half a mile out to sea and 30 feet down.

Marine biologists Dale Sarver and Neil Anthony Sims raise Hawaiian amberjack, a native species that is called kampachi in Japan. Unlike most fish farms, Kona fish are raised in a controlled environment from hatch until harvest. The fish, called Kona Kampachi, retails for about $20 a pound.

The payoff: Former Horizon Organic chairman Tom McCloskey, now Kona Blue's chairman, says sales will reach $8 million to $10 million in 2007, up from just $2 million last year. Kona Blue is sold at select Whole Foods stores and served at the tables of top restaurants like the French Laundry in California's Napa Valley.

The opportunity: Kona Blue does not yet have any direct competitors employing its fish-farming techniques, though a couple of companies are gearing up their operations.