The document is about aquaponics, which is a self-sustaining system that combines aquaculture and hydroponics. In an aquaponics system, fish waste provides nutrients for plants to grow without soil. The plants filter the water, which is then recirculated to the fish tanks. Aquaponics systems do not require chemical fertilizers or regular maintenance. The document discusses how aquaponics works, its benefits such as producing food with minimal water and space, and its potential applications to address food shortages.