Even fish can work.  The amazing acts like eating and producing waste that fish do, is the perfect fertilizer for growing plants.  Aquaponics is just like a natural ecosystem.

Aquaponics represents the relationship between water, aquatic life, bacteria, nutrient dynamics, and plants which grow together in  places like waterways  throughout the  world. 

Exchanging the waste by-product from the fish as a food for the bacteria, to be converted into a perfect fertilizer for the plants, and then  to return the water in a clean and safe form to the fish is how these systems work creating tremendous yields.