Aquaponics: an introduction
Aquaponics has great potential both in industry and as an urban agricultural system. Fish and plants are raised together without soil and utilizing the same water. Key to this arrangement is that plants are able to absorb the metabolic wastes produced by fish and use them as nutrients, while purifying the water that is then re-circulated back to the fish.
Aquaponics is attractive because it is inherently more sustainable than traditional aquaculture and agriculture on their own, and has the potential to compete with traditional agriculture, since it requires less fertilizer, water, and land. The water can be recirculated, nitrogen for the plants comes from fish waste, and the land does not even need to be farmable. Conventional fish farms require large amounts of freshwater, a valuable resource, that is often polluted by fish wastes and released into the surrounding environment. Conventional plant farms also require water for irrigation, as well as arable land and fertilizer. Aquaponics can mitigate these issues, since fish and plants are grown in the same space with minimal water input.
The Kunia Farms lettuce growing troughs
A variety of different fish species and plants can be combined in an aquaponics system, from koi fish and tilapia to greens, herbs, and tomatoes. Hawai’i is already home to several dozen lettuce and tilapia farms, some of which can produce 70,000 heads of lettuce on only one acre of land . Iron, potassium, and calcium are the only nutrients that must be provided, since others are produced by the tilapia, and any water added to the system comes from rainfall.
Lettuce seedlings at Kunia Farms
In urban settings, would it be possible to apply aquaponics on a smaller scale? One that has the potential to produce a myriad of vegetables, that would be able to farm fish locally in relatively small spaces, and provide healthy, local food for urban residents?
We know that, depending on location, aquaponics can have an economic and resource use advantage over traditional farming. Can it also be scaled, both large and small, to address systemic and societal problems, such as those inherent in the agricultural industry, and also, more importantly, with eliminating urban food deserts through local access to food?
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Hussain, T., Verma, A. K., Tiwari, V. K., Prakash, C., Rathore, G., Shete, A. P. and Nuwansi, K. K. T. (2014), Optimizing Koi Carp, Cyprinus carpio var. Koi (Linnaeus, 1758), Stocking Density and Nutrient Recycling With Spinach in an Aquaponic System. J World Aquacult Soc, 45: 652–661. doi:10.1111/jwas.12159
Lastiri, D. R., Slinkert, T., Cappon, H. J., Baganz, D., Staaks, G., & Keesman, K. J. (2016). Model of an aquaponic system for minimised water, energy and nitrogen requirements. Water Science and Technology, 74(1), 30-37. doi:10.2166/wst.2016.127
Tokunaga, K., Tamaru, C., Ako, H. and Leung, P. (2015), Economics of Small-scale Commercial Aquaponics in Hawai‘i. J World Aquacult Soc, 46: 20–32. doi:10.1111/jwas.12173
Tyson, R. V., Treadwell, D. D., & Simonne, E. H. (2011, February). Opportunities and Challenges to Sustainability in Aquaponic Systems. HortTechnology, 21(1), 6-13. Retrieved September, 14, from http://horttech.ashspublications.org/content/21/1/6.full.pdf html
 Tokunaga, Tamaru, Ako, & Leung, 2015; Hussain et al., 2014; Tyson, Treadwell, & Simonne, 2011
 Tyson et al., 2011
 Hussain et al., 2014
 Tokunaga et al., 2015
 Hussain et al., 2014; Espinosa Moya et al., 2016; Lastiri et al., 2016