Adam Harwood has 10,000 of the hardest-working fish in San Marcos.

Those fish—and a lot of hard work on the part of Harwood and his team—are the driving forces behind the bounty of food produced at Lilypad Farm each month.

Lilypad Farm uses aquaponics, the combination of fish and plants in a recirculating system, to produce its food.

"Not only do I have great food, I have connoisseur's food," Harwood said. "I put food in the hands of people, and I only want people to have the best food possible."

Aquaponics has been studied since 1981, and the method was perfected through the work of James Rakocy, Michael Masser and others at the University of the Virgin Islands at St. Croix. At Lilypad Farm, Harwood has built three buildings on his 2-acre property, each with two fish tanks and two plant beds measuring 8 feet wide, 72 feet long and 16 inches deep. The fish's nutrient-rich feces are siphoned out of the tanks, filtered and the water fed into the plant beds, where it is soaked up. The nutrient-rich water, which Harwood calls "bloom blaster," produces plants that have caused more than a few of the farm's visitors to wonder aloud how the plants got so big.

"When you go from nitrite to nitrate and you get all that glorious growth, that's God speaking," Harwood said.

The transition from small-business owner to aquaponic farmer took Adam, his wife Susan and their 5-month-old child to the Virgin Islands in 2008. After selling the family's house and business, Harwood studied under the aquaculturists and scientists who perfected the aquaponic method. When he returned to San Marcos, he set up a system identical to the one he had seen in the Virgin Islands.

Now his vegetables can be found at Palmer's Restaurant Bar and Courtyard in San Marcos, among other local restaurants.

"The cool thing is the stuff is still alive when he sells it to us," Palmer's owner Monty Sheffield said. "It's still on the root. You can't get any fresher than that."

In addition to vegetables, when the tilapia that occupy the fish tanks are fully grown, they are harvested and sold.

Adam and Susan said they are turning their attention to training the world's future aquaculturalists.

The Harwoods have developed a smaller version of their system that Susan, who holds a master's degree in education, believes would fit well in a school setting.

"In my mind it belongs in a school, where you can take kids out of the classroom and show them how to measure for parts per million and dissolved oxygen and pH and iron and ammonia, and see it working. It's a hands-on education. That's the future in my mind; empowering young people."

While other practices such as hydroponics and transgardening—farming methods that involve certain parts of aquaponics but change or add other elements—are effective, Harwood said he believes his crop speaks for the efficacy of pure aquaponics.

People are beginning to take notice, too. For example, on May 9, the word "aquaponics" was added to Merriam-Webster's online dictionary. In November researchers from Johns Hopkins University and Kentucky State University visited Harwood's farm in San Marcos to study his method.

"I built a farm," Harwood said. "I didn't buy a farm. I grew a business. You don't just buy a business. I've built a farm that will stay here infinitum. This is a sustainable farm."