Aquaponics is using fish in fish tanks hooked up to plants in a symbiotic nutrient cycle, to make both grow and thrive.
Mark Berger has an aquaponics setup in the South Side, under the Pittsburgh Aquaponics name that he'll be taking me and others to see on Saturday, and I just realized we might as well make it open to the public, to see if we could introduce more people to this practice. Anyone's welcome. :)
The picture above is from Growing Power's aquaponics setup--Mark says his is not terribly photogenic, and it's really just a demonstration to show how you can do it in your home or garage, not a large thing--but the above is still a good picture to indicate what all this can look like.
Mark's blog is here: http://pittsburghaquaponics.org/
[There's another site with the same name/brand, but it's not the same one.]