Aquaculture
Several years ago, we added fish to our home-grown harvest. We've found that raising fish in a "barrel" doesn't require as much effort as we imagined.
After a year or two of aquaculture, we went to aquaponics--that's a combination of aquaculture and hydroponics, making a symbiotic (mutually beneficial) environment. In other words, the fish wastes supply nutrients to plants, and plants by using the waste, clean up the water that the fish live in.
The fish water is pumped to the plant beds filled with gravel (or other growing media) where it feeds our plants (greens, cucumbers, tomatoes, herbs, etc.) and then filters through the gravel and drains back into fish tank.
Click here for a videos, pictures, and an explanation of Aquaponics.
Thanks to politicians and bureaucrats, water in California is at times in short supply. This system saves water--so far, due to transpiration and evaporation, we have had to add only a fraction of what we use in a soil garden to keep the same number of plants watered. The only other regular input to the system is fish food. We occasionally add chelated iron and liquid seaweed fertilizer.