July 25, 2012 | Noelle Swan

Ed Osmun of E&T Farms in Barnstable, Massachusetts has been chewing on the idea of growing food in a controlled environment for nearly 40 years. Seven years ago, he put it into practice when he and his wife scaled back their beekeeping operation to build an aquaponic farm, a closed-loop farming system linking hydroponically grown vegetables and fish tanks of ornamental koi. In addition to the aquaponic farm, E&T Farms still maintains 200 beehives, one greenhouse that grows root vegetables through the winter, and some outdoor gardens with a variety of gourds. They sell honey, produce, and bags of mixed greens at the farm to five local stores, and at several area farmers markets. The koi is sold to area water-garden shops.

Aquaponic Farming in New England

Within a high-tech greenhouse, safe from the harsh winter winds and blazing summer heat of Cape Cod, greens such as lettuce, basil, and arugula bathe their roots in basins of water that flows from the fish tank and back again through a series of pumps. The plants feed on the koi’s nutrient rich waste and keep the water fresh and clean for the fish.

Despite having researched aquaponics for quite a while before starting this venture, Osmun says he still hit a steep learning curve. He says the truest piece of advice he found in all of his research was “if you want to make a small fortune in aquaponics, start with a large one.” The Osmuns sunk all of their savings into installation of the farm and have not turned a profit quite yet.

The aquaponic farm is housed inside a high-tech greenhouse. Double-walled, polycarbonate panels and radiant floor heaters make it possible to grow year-round despite the often harsh seasons of New England. A computer system monitors humidity levels and opens up the roof to vent as needed. In the summer, a shade cloth covers the greenhouse ¾ of the day to keep it from overheating. Costs of maintaining the climate control system continue long after the initial investment. Osmun says these energy costs have been one of the most difficult challenges.

Besides financial hurdles, Osmun says that it took a good deal of trial and error to find the right type of fish for his system. In the beginning, they tried raising largemouth bass, trout and tilapia, but found the high cost of heating the tanks to be a major obstacle. Tilapia, for instance, need a consistent water temperature of 80 degrees. Koi can tolerate much colder temperatures, even overwintering outside once in their permanent water garden home. For now, E&T has found a comfortable niche selling ornamental koi to the water garden market, though Osmun says he is still interested in finding a way to produce some seafood. Right now, he is looking into freshwater prawns and says that local chefs have expressed interest in adding prawns to their menu should it prove viable to raise them in a similar aquaponic system.

Selecting the right crops proved to be challenging as well. In the beginning, Osmun dreamed of bringing strawberries to local indoor farmers markets in the middle of January. He says he tried five different varieties with little success. Only one ever fruited and the strawberries were so soft that they collapsed between his fingers when he tried to pick them. In general, he found that fruiting vegetables did not fair well in his system. Crops like tomatoes and peppers require heavy feeding. Hydroponic farmers can accommodate this by tweaking their nutrient solution. However, in aquaponic farming, added nutrients can compromise the health of the fish. He found that arugula, lettuce, several varieties of basil, and microgreens all thrived on the nutrients that could be provided by the fish.

Now that Osmun has found the right plants and fish to complement each other, he performs a delicate balancing act to maintain the system and keep both thriving. He says he watches the fish closely for signs of stress. He knows that slightly increasing the salinity of the water could help to boost their immune system. However, too much salt could kill the plants. He says that he makes an extra effort to ensure that he starts out with healthy fish. When new fish come in from Malaysia, he isolates them in a separate tank that is not connected to hydroponics and tests the water for evidence of bacteria or disease before introducing them to the aquaponic system. Every decision has to be considered in terms of how it will affect both the fish and the plants. Even pesticides approved for organic farming could be harmful to the koi, Osmun says. Instead, he relies on beneficial insects. He fondly refers to his ladybugs and parasitic wasps as his “bio-security agents.”

The Osmuns have one full-time employee who helps them manage the greenhouses and a part-time employee that helps in the outdoor garden. In planning, Osmun says they think more in terms of increasing the variety of products that they offer rather than the quantity. In addition to possibly adding prawns to the aquaponic green house, he hopes to install a mushroom room in a hoop house.