Unlike most farm-raised fish, which must eat other fish to grow, tilapia is an omnivore that can thrive on soy, corn, wheat, algae and plant waste. Plus, tilapia farms can be housed indoors where resulting wastewater and pollution are better controlled. Thirty thousand pounds of tilapia can be raised on just three acres annually — the same amount of space it takes to raise one 650-pound cow. — Slowfoodnation.org