Johns Hopkins University's Center for a Livable Future on Aquaponics Lessons Learned

Fish farming often gets a bad rap because of problems like overcrowded cage and pen conditions and water pollution in offshore pens. There are much better ways to farm fish, like land-based recirculating farms that often include the use of the fish waste to fertilize produce grown hydroponically (what's known as 'aquaponics'). People might not be familiar with this type of fish farming (or produce farming either, for that matter), so we thought it would be a good time to introduce our readers to a few of the farmers that grow both fish and produce on their farms.

This week we're talking about how aquaponics currently fits into our food system with Aquaponics Project Director David Love, Farm Manager Laura Genello and Public Health and Sustainable Aquaculture Project Director Jillian Fry, from the Center for a Livable Future (CLF) at the Johns Hopkins Bloomberg School of Public Health.

CLF's aquaponics lab, located at the Cylburn Arboretum in Baltimore, Maryland, was installed in a 1,200 square foot hoop house that was converted into a recirculating fish and produce farm in partnership with the city of Baltimore. They raise tilapia and grow a variety of plants with a goal of employing and evaluating techniques that impact the economics of both parts of the system. According to their website, they've learned that "aquaculture inspires dialogue about sustainability and the food system." Read on for some of that dialogue.

Why did you start an aquaponics system at JHU? Could you give a brief history of its evolution?

We started the Aquaponics Project in 2011 to raise awareness of, and increase the body of knowledge about aquaponics, including research on economic, social and ecological aspects of aquaponics.  The project was run by the Center for a Livable Future's Public Health and Sustainable Aquaculture Project on the grounds of the Cylburn Arboretum. Over the past four years we have hosted over 5,800 visitors, produced over 3,000 pounds of food and generated over $18,000 in sales.

The greatest asset of the Aquaponics Project is its capacity to engage visitors in conversations about food production and food systems. This was evident in our interactions with individuals who came for tours of the project, and school groups who visited the project to augment their classroom learning. Based on these lessons, we decided to continue the project with a focus on education; starting in the summer of 2015 we renamed the project the Food System Lab @ Cylburn. We still grow some food for sale at farmers markets, but focus more on delivering impactful educational programs targeting middle- and high-school students, college students and adults.

At the Food System Lab, we are excited to showcase different aspects of the food system, including aquaculture, raised bed gardening, vermiculture (worm composting), crickets, food mapping and other rotating exhibits to increase visitors' exposure to food system thinking. If you live in the Baltimore-Washington, DC region, consider stopping by to see the new programs we offer!

Tell me about your system. How big is it? What and how much do you raise/grow? What do you feed your fish?

At its largest size, the aquaponics raft system was 2,600 gallons in volume and 244 square feet of hydroponic beds housed within a 1,250 square foot hoop house (we reduced the size in 2015 to make room for other activities and to host larger groups). We raise Nile and blue tilapia and feed them a diet of Ziegler fish food augmented with duckweed. Our tilapia waste is broken down by bacteria and used to fertilize a variety of leafy green crops grown hydroponically and to irrigate raised beds and planters. Some of our favorite crops for performance and marketability are basil, chard, celery, watercress and sorrel.

Now that your system is established, how is it different from your expectations going in?

These last four years have taught us a lot, not only about aquaponics, but also the food system as a whole, and we have been inspired by the countless discussions of a more sustainable future that have taken place inside the greenhouse. Several challenges we see for aquaponics (as practiced in the US) are:

  • The reliance on specialized parts (plastic parts, PVC pipe, pumps, and aerators) and high start-up costs;
  • The dependence on fossil fuel, store-bought feed and tilapia - a non-native fish that thrives in tropical climates and not in temperate Baltimore, Maryland. [We performed an economic analysis of our small-scale system and found that it costs more to raise tilapia than the price we could get selling them (read our  study in the journal Aquacultural Engineering)]; and
  • A steep learning curve. We made our fair share of mistakes in our first year as we learned both about hydroponics and aquaculture.

What obstacles did you have to overcome while establishing the farm?

The biggest obstacles were physical and technical: performing farm labor is hard work and running a small farm means fixing things when they break. We came to enjoy the feeling of success and relief after hours of knees-in-the-mud plumbing repairs to fix leaks, and long spring harvest days, when a car full of deep green produce is evidence of a job well done.

Did you ever lose fish or crops?

During the first six months in production we lost about 10 percent of our fish due to an equipment malfunction, and since then have had a very low (less than 1 percent) mortality rate. Our biggest challenge raising crops comes from a high pest pressure in the summer. We fight pests, such as spider mites, using predatory insects, and occasionally lose plants to fungal diseases, such as downy mildew.

Where do you sell your products?

We sell crops weekly at the Saturday Waverly Farmers' Market at a shared table with members of the Farm Alliance of Baltimore. We sell tilapia occasionally and in limited numbers to Woodberry Kitchen, a farm-to-table restaurant run by chef Spike Gjerde, a 2015 James Beard Award winner.

What has been the best/most surprising response from kids, teachers or community groups that have toured your farm?

We use the aquaponics system as part of a broader educational program on the food system, and we think this helps set us apart from other farms that provide tours. On a personal note, we have enjoyed witnessing the epiphanies of a group of eighth grade students as they discover this new way to raise food, and how the entire chain of production, from farm-to-fork, impacts their lives and the planet. We also love to hear excited shouts from kids as they discover the mosquito fish, snails, worms and numerous forms of life thriving on our farm.

Do you have any advice for people interested in learning more about aquaponics or even trying their hand at it?

If you want to learn more about aquaponics and live in the Baltimore-Washington, DC region, come visit our greenhouse, or find us on the web at Food System Lab @ Cylburn. If you want to build an aquaponics system, we recommend starting small and with used parts and supplies wherever possible. The average soil-based gardener spends about $100 per year on their garden, which should be a good price guide for spending on a home aquaponics system, but many aquaponics gardeners find that they spend more. As long as you recognize that aquaponics might not be economical, building and running your own system can be fun and rewarding in many other ways. For more information on building a system, check out the US Department of Agriculture's website.

Could you talk a little about the role aquaponics (and recirculating farms) plays in our food system?

There is certainly a place for aquaponics as an education tool in schools and at the household level for individuals who like blending gardening, aquaculture and engineering/technology. We have found through surveys that aquaponics gardeners are more often men with higher levels of disposable income, and are motivated by the desire to grow their own food, improve their health and improve environmental sustainability. Whether gardeners are achieving food security may be less important than whether they are having fun and getting exposure to farming. We have learned through conversations with visitors that aquaponics excites and inspires people who have not previously thought about food system issues to question where their food comes from. [Read our  study in the Journal of Agriculture, Food Systems, and Community Development].

How do you respond when people ask you, "What fish should I order?"

We share advice given by Paul Greenberg - author of "American Catch" and well respected voice on seafood sustainability - who puts an interesting spin on Michael Pollen's now famous food rules: "Eat food. Not too much. Mostly plants." For seafood, Greenberg recommends "Eat American seafood. A much greater variety than we currently do. Mostly farmed filter feeders." For more on Greenberg's advice read his Op-Ed in the New York Times called Three Simple Rules for Eating Seafood.

This interview has been edited for brevity.