Aquaponics

Have you ever heard of Aquaponics? It's a mix between hydraponics(the growing of plats in nutrient rich water) and aquaculture(the raising of fish). In both of those systems you have to dispose of water because it gets too polluted, either because of fish waste or too much nutrients in the water. With Aquaponics, you don't have that issue since the fish waste is used as nutrients for the plants, and the plants filter the water for the fish. And that my friends is a symbiotic relationship.
I think it would make a great renewable food source, especially if you had a tilapia breeding colony.

Here is some information.

backyardaquaponics.com

And some info on tilapia farming(unfortunately, it is illegal to raise tilapia in some states. But you can still use catfish, perch, and tons of other fish)

Tilapia Farming at Home

Hope it helps someone!