Portable fish farm at Growing Power in Milwaukee, Wisconsin. Photo: Steven Walling. Accessed from the Wikimedia Commons.
Portable fish farm at Growing Power in Milwaukee, Wisconsin. Photo: Steven Walling. Accessed from the Wikimedia Commons.

With the recent increase in popularity of urban farming on the rise, the question arises: how much food can actually be generated in the city?  One technique that can increase calories per square foot while also reducing fertilizer and pesticide use is aquaponics.  Aquaponics is a food-production strategy that links aquaculture, the raising of fish and shellfish for food, and hydroponics, the growing of plants outside of a soil medium, to the benefit of both.

The joined system reduces resource input (water and fertilizer) and waste compared to either system individually.  Wastes from the fish-rearing tank contain ammonia which is toxic to the fish.  These wastes are brought through a shallow medium containing nitrogen-fixing bacteria that break down the ammonia into nitrites and, in a second step, into nitrates.  The nitrate water is passed through plant growing beds where plants filter out the nitrates, using them for growth.  The water, now filtered, returns to the fish-rearing tank.

Systems like these are being used both at a commercial scale as well as in backyards.  Aquaponics startups are showing up in old warehouses in cities like Chicago and Milwaukee. 312 Aquaponics in Chicago shares its building—a former meat-packing plant—with a kombucha-brewing business and a microbrewery (1).  Sweet Water Organics, in an old Milwaukee warehouse, produces a range of greens and vegetables, herbs, oyster mushrooms, perch, and tilapia (2).

A quick internet search for “DIY Aquaponics” brings up many styles and techniques to help the backyard gardener, or even an indoor gardener, build a variety of sizes of aquaponics systems.

The reuse of water, the vertical stackability of the systems, and the conversion of wastes into nutrients makes aquaponics systems ideal for urban areas and arid regions.

(1) MARTHA IRVINE – AP National, Writer. “In An Old Chicago Meat Plant, Greens And Fish Grow.” AP Top News Package (2012): Newspaper Source Plus. Web. 2 Aug. 2013.

(2). Sweet Water Organics. 2013. Swet Water Organics Products and Services, http://sweetwater-organic.com/products_services (8/2/13).

Post by Sarah Schramm.

Sarah is a graduate student at the University of Virginia, pursuing a Masters in Landscape Architecture.