Who needs soil when you have a fish tank? “Aquaponics” combines growing plants in water, or hydroponics, with fish cultivation, or aquaculture. It’s a symbiotic process that has its roots in Asian farming practices reaching back thousands of years. When used well, aquaponics can increase local food production and make communities more resilient – all without creating pollution or using scarce resources, such as oil.
It begins with fish poo and pee, both of which contain lots of ammonia. Worms that live in rooting substrates break the solids down and then bacteria convert the ammonia into nitrate, which acts as a fertiliser. The plants absorb the nitrate and effectively filter the water for the fish. By which point the fish will once again need the toilet, and so on. It’s a virtuous circle.