Fish and veggies feed each other

An African farmer has developed a turnkey aquaponic system which combines aquaculture (fish farming) and hydroponics (growing plants without soil) in controlled conditions in a greenhouse.
The concept is simple and requires no special skills while providing year round, fresh fish and organic vegetables irrespective of seasonal or climatic w {mosimage}An African farmer has developed a turnkey aquaponic system which combines aquaculture (fish farming) and hydroponics (growing plants without soil) in controlled conditions in a greenhouse.
The concept is simple and requires no special skills while providing year round, fresh fish and organic vegetables irrespective of seasonal or climatic weather changes. The innovation has won Ken Konschel of South Africa an Inventor Award from Swedish based International Foundation for Science.
In aquaponics, the nutrient wastes from the fish are used to fertilise hydroponic vegetable beds via irrigation. Plant roots and bacteria remove nutrients such as fish waste, algae and excess fish food from the water that would otherwise build up to toxic levels in the fish tank. These nutrients serve as liquid fertilizer to the hydroponically grown vegetables. In turn, the hydroponic beds function as a filter so that the water can be recirculated back into the fish tanks under pressure to provide aeration for the fish.
Konschel sells his fish whole, fresh directly to the community.
Aquaponics is not a new invention, says Konschel. Innovative, however, is the concept of "the fish feed the plants, the plants feed the fish and the worms, and the worms feed the fish, the fish feed man". He also breeds chickens whose waste is used as compost in the vegetable gardens and to feed worms, which in turn are fed to the fish.
Konschel recommends two species of tilapia (bream) because they are easy to breed and tolerate a wide range of water quality conditions. Tilapia Rendalli are herbivores feeding on lettuce, carrot tops, cabbage, spinach and lawn cuttings. Oreochromis Mossambicus eat worms, algae, crickets, flying insects and detritus. This combination ensures nothing goes to waste, but trout or catfish can be used instead, depending on the climatic conditions under which the system functions.
As the system is recirculating, it uses little water. Water is only lost to evaporation and plant uptake. The system can be run on land that is unsuited to traditional agricultural crop production and has limited water supplies. No chemicals or additional fertilizers are required.
An aquaponic system can be run on either small or commercial scale, in industrial or rural settings. Konschel has formed a company, Aquaponics Africa, which supplies and installs complete systems, ranging in sizes to suit individual households, schools, clinics, co-operatives or large scale commercial enterprises. Systems include fish, vegetable seedlings and fish food.
Training is essential before venturing into aquaponics and the company provides practical and theoretical on-site training in skills relating to aquaculture, hydroponics, water quality, growth rates, fish health an the like.
Konschel says a commercial size fish tank with a volume of 40,000l sustains approximately 2t fish in varying sizes to ensure a steady harvest. It has a planted area of 120sqm divided into three vegetable beds. This system would cost around R350,000 (US$50,000) to install in South Africa. The company will also install units elsewhere in Africa, but prices will vary according to location.
Konschel has already installed a system on a mine in South Africa and has received requests from Malawi, Botswana and Zambia.
Aquaponics Africa: Tel +27-35- 7724586 fax +27-35 7724584; cell +27-82-8528588; aquaponicsafrica@zulucom.net