Aquaponics is the symbiotic cultivation of plants and aquatic animals in a recirculating environment.
Aquatic animal effluent (for example fish waste) accumulates in water as a by-product of keeping them in a closed system or tank (for example a recirculating aquaculture system). The effluent-rich water becomes high in plant nutrients but this is correspondingly toxic to the aquatic animal.
Plants are grown in a way (for example a hydroponic system) that enables them to utilize the nutrient-rich water. The plants take up the nutrients, reducing or eliminating the water’s toxicity for the aquatic animal.
The water, now clean, is returned to the aquatic animal environment and the cycle continues. Aquaponic systems do not discharge or exchange water. The systems rely on the natural relationship between the aquatic animals and the plants to maintain the environment. Water is only added to replace water loss from absorption by the plants or evaporation into the air.
Aquaponic systems vary in size from small indoor units to large commercial units. They can use fresh or salt water depending on the type of aquatic animal and vegetation.
Some consider Aztec chinampas to be the first example of aquaponics. Others refer to ancient Egypt. Either way, it is clear that aquaponics has ancient roots.
“Integrated vegetable growing and fish farming polyculture systems have long been used in Far Eastern countries such as China and Thailand. Farm wastes are commonly added as feed to fish ponds and fish are often cultured in flooded rice paddies.”
Aquaponics in the United States
Many institutions and enterprises followed on the efforts (replicated peer-reviewed research, active publication, dissemination and technology transfer) at North Carolina State University; notably by the University of Arizona Environmental Research Labs, NASA/CELSS, S&S Aquafarms, The Freshwater Institute, University of Arkansas , Bioshelters, Inc , Global Aquatics, Inslee Fish Farms and others who carried out (mostly proprietary and unpublished) ‘research and development’ of aquaponics.
From the 1980s to present day the two distinct aquaponic systems are;
1) “Deep Water” or “Raft Culture” aquaponics which is the primarily research carried out at the University of the Virgin Islands under the guidance of Dr. James Rakocy and;
2) Reciprocating aquaponics (“Ebb and Flow” or “Flood and Drain”) based on the techniques developed by Mark McMurtry, et al. at NCSU (such as that implemented by Tom and Paula Speraneo of S&S Aquafarms in West Plains, Missouri.
The University of the Virgin Islands Aquaculture Program has developed an aquaponic system through over 20 years of research into its design and operation. The system can produce over 10,000 lbs. of tilapia annually and a variety of vegetables that are harvested weekly in staggered production (lettuce and basil) or as needed by other fruiting crops (okra, cantaloupe, peppers, tomatoes etc.) The aquaculture program promotes several principles of aquaponics that can be applied to any size system, from hobby-scale to commercial-scale. These principles include a) system design that balances feed input to vegetable growing area, b) constant input of feed by staggering fish stocking, c) constant nutrient uptake by staggering vegetable production, d) continuous water flow and e) maintaining pH of 7.0. Other guidelines also apply and lead farmers to productive and profitable enterprises.
The University of the Virgin Islands teaches a course each June, the “International Aquaponics and Tilapia Aquaculture Course” to participants from around the globe. These individuals return home to develop their own commercial enterprises based on the aquaponic principles taught in the course.