Out back, Meir Lazar is putting the finishing touches on a bigger new home for the fish inside a plastic-covered greenhouse. There, he hopes, the waste from the fish he's tending will help him raise enough lettuce, tomatoes and other produce to feed his family of five year-round.
Sustainability is more than a buzzword for Lazar, 32, a computer systems administrator and teacher who's pursuing aquaponics in his small suburban backyard off Greenspring Avenue. He said he's inspired in part by news reports about food tainted by pesticides, bacteria and even radiation from the Japanese nuclear disaster last year.
"I think it's incumbent on every person to start growing their own food so they can take back some of the control over their health, over what's in their food," he said. "Plus, you have a deeper appreciation of what you've grown and what you're about to eat."
Aquaponics has been around at least since the early 1970s, when the New Alchemy Institute in Massachusetts started promoting backyard fish farming and organic gardening inside greenhouses it dubbed "bioshelters."
It has gained new attention in recent years, not just from advocates of sustainable agriculture but from those who believe aquaponics can help fill needs in poor urban communities for healthier food and jobs.
One of the aquaponics ventures taking shape in Baltimore is at the Cylburn Aboretum. Sponsored by the Johns Hopkins Center for a Livable Future, it would raise tilapia and produce for sale in the city's "food deserts," where fresh locally grown produce isn't readily available at corner markets and convenience stores.
With a budget of about $10,000 and the help of interns, friends and volunteers, microbiologist Dave Love has assembled his fish and produce farm. Four blue 250-gallon plastic tanks will be used to raise tilapia, which are hardy and fast-growing. The fish excrement and nutrient-fouled water are to be piped from the bottom of the tanks into a couple of other tanks where the ammonia in the wastewater is converted by bacterial action into a form of nitrogen that can feed plants.
The enriched water is then to be piped through two large shallow troughs in which Love plans to raise leafy greens and other vegetables. Thus cleaned up, the water is then pumped back to the fish tanks.
"It's sort of like the next step into urban agriculture," Love said.