One of the newer innovations in food production is a closed-loop system called aquaponics, where fish and veggies are grown together using recirculated water. With population levels set to reach 9.7 billion by 2050, more mouths to feed calls for food production methods that are both eco-friendly and resource-conscious. The world’s wild fish stocks are decreasing, and production of farmed fish has doubled in the last 15 years. By moving these farms onto land, commercial scale aquaponics operations could revolutionize food production, using less space, water and energy than ever before.

Here’s how it works

In a recirculating system, fish tank water is pumped to vegetables in a greenhouse. Aquaponics uses no soil, and instead the plants sit cozily in floating foam rafts with roots hanging down into water-filled tubs. Fish excrement acts as a natural fertilizer, and in turn, the veggies purify the water in this mutually beneficial system.

The third player in the system is the extremely important beneficial bacteria that break down fish waste into a form of nitrogen that plants can use to grow. Without them, the waste wouldn’t get properly recycled.

Two inputs power the system: fish feed and energy, and both can be sustainable if sourced properly. Carnivorous fish such as salmon rely on protein-based feed typically sourced from forage fish. Targeting these fish can be unsustainable, however some fisheries are improving their environmental impact through assessments and responsible fishing plans. The use of insects as feed instead of forage fish, and reliance on renewable energy are good ways to make these systems more eco-friendly. Rome-based aquaponics venture The Circle has operated using solar power since 2018, and their koi fish are fed with microalgae-based feed.

While the vast majority of aquaponics is freshwater, pioneering research into the use of saltwater species is catching up.

Read the rest of Ariella Simke‘s article here at Forbes