http://urbanfarmingtrends.com/hydroponics/aquaponics/ Aquaponics: a hydroponic system in which the waste water from aquatic life is utilized to feed the plants instead of premixed nutrient solutions. This in turn filters the water for the aquatic life. This creates a symbiotic relationship between the two. Most hydroponic systems can be aquaponic systems just by adding fish. They just have to be closed systems. See the article on Hydroponics http://urbanfarmingtrends.com/hydroponics/different-types/.