"Both the Nile perch and the tomato thrive in warm environments, so we came up with the idea to grow them together. We developed a special sustainable method of growing, and put a patent on an aquaponics greenhouse," explained head of the project, Dr. Werner Kloas of the Leibniz Institute of Freshwater Ecology and Inland Fisheries in Berlin. Aquaponics is a combination of hydroponics (growing plants in water, without soil, using mineral solutions) and aquaculture (or aquafarming – farming aquatic organisms).

"When digesting food, the fish release by-products, which are extracted through gills and feces. With the help of various bacteria, these are then turned into nutrients, taken by the plants to use for their own growth. By using these nutrients, the plants simultaneously purify the water, which is then consumed by fish, and the cycle is completed," explained Kloas, who is in charge of the aquaponics greenhouse in the outskirts of Berlin.

The point of aquaponics is the constant cycling of water and the nutrients it brings. "It's a sustainable method of farming, where the fish food is used to feed the fish first, and later to also feed the plants," Kloas continued. Who would have thought that fish feces can double as a nutrient generator for a vegetable garden?