For the home 
aquaculture level, I just read a great passage from the book Toolbox for Sustainable City Living. 
 Very simple, very smart aquaculture for the water geeks who like to play around in the backyard. I'd *love* to see one of these in action! 
 I can't post the chapter here, but I'll post the book.  
http://www.southendpress.org/2006/items/87804