Fish

Why Fish?

Raising fish in urban areas offers perhaps the most efficient opportunity to raise a large quantity of high-quality protein. Fish can be fed on food wastes from restaurants and supermarkets, and can be grown in intensive systems that can yield tens of thousands of pounds of healthy protein in as small of a plot as a typical empty city lot.

Recirculating Aquaponics Systems

• Water with fish wastes is pumped up to flood-irrigate vegetables and herbs (often stacked two levels above the pond), which grow incredibly fast with the extra nitrogen provided by the fish.  The water then recirculates back into the pond, completing the closed-loop system
• Plants can be grown in a soil-less substrate, in gravel, or in pots filled with worm castings and compost
• The water is cleaned of its excess nitrogen by the plants and the beneficial bacteria living on the gravel, so that when it returns to the tank, it is clean enough for the fish to thrive
• Before trickling back into the pond, the water can be sent through an additional low-tech sand filter to provide insurance that the water will be sufficiently clean enough for the fish
• The water must also be continously flowing, and additional pumps are used to oxygenate the water.
• Close monitoring of oxygen and nitrate levels are essential to maintain a successful system

Good Species of Fish for Recirculating Aquaponics Systems

Tilapia

• The most common species grown in urban aquaculture around the world
• Tolerant of crowding and less than pristine water quality
• Easty to feed: likes earthworms, duckweed, veggie scraps
• Also a filter feeder, eating microalgae suspended in water, a food niche at the bottom of the food chain exploited by few fish species
• Drawback: won't survive less th 55 degree water, and thrives in warm water aroun 85 degrees

Urban Aquaponics in Reclaimed Urban Warehouses/Empty Lots

Aquaponics holds incredible potential for small business startups/cooperatives to form in urban areas.  Empty lots and abandoned warehouses present perfect sites for urban aquaponics systems.

Check out the pioneering work of Growing Power and SweetWater Organics is Milwaukee, Wisconsin to see this visionary work in action!