Aquaponics:

Aquaponics is the cultivation of plants without soil in a recirculating environment that combines hydroponics (growing plants without soil) and aquaculture (raising fish and other aquatic creatures). In aquaponics, the waste produced by the fish is transformed into nutrients for the plants by nitrifying bacteria. To flourish, plant roots take up these nutrients. For the fish to survive, the plant roots purify and filter the water.