Aquaponics
People have been raising fish with plants for thousands of years because of their symbiotic relationship. Plants use the natural fertilizer produced by the fish, and in doing so, filter the water so that the fish stay healthy. This is how natural ecosystems work. Closed loop aquaponics uses 90% less water than traditional farming since the water is constantly being cleaned and recirculated. The only water loss is from evaporation and what the plants use to grow.
Aquaponics systems grow food faster and in much less space than soil based farming, especially when grown vertically. Traditional farming tends to use standard fertilizers made from fossil fuels that can contaminate streams and groundwater. The nutrient rich water in aquaponics is a perfect natural organic fertilizer. Growing in a greenhouse reduces the chances of pests getting in and allows you to produce fresh food all year. It is completely organic since pesticides would kill the fish.