Rob Torcellini bought a $700 greenhouse kit to grow more vegetables in his backyard. Then he added fish to get rid of a mosquito problem and before long he was a committed aquaponic gardener. Now his 10 by 12 foot greenhouse is filled with not only vegetables, but fish. And the best part is: the poo from that fish is what fertilizes his garden. Aquaponics combines fish farming (aquaculture) with the practice of raising plants in water (hydroponics).