I am convinced that here is huge potential for raising “Crawdads” in urban farms.
They can be fed vegetable waste and hay from the farm, and: “Freshwater crayfish are highly regarded as a delicacy as they are very similar to shrimp or lobster in taste and texture…high protein and low-fat.”
I found a few books about raising Crayfish, it would be worthwhile exploring possibilities for integrating them into a medium-scale aquaponics system:
http://www.rampumps.com/craybook.htm