Robert,
Ditto LakeL.
Also, I'd offer you my brief experience from several years ago in a small pond (1/4 acre) stocked w/Tilapia and no predators. They multiplied like crazy, stunted, and when die-off happened, 3 to 5 inch Tilapia were stacked up along the shoreline everywhere. Without predation, they overpopulate quickly and produce staggering numbers of offspring.
However, if you are interested in growing them as a food item, you may want to consider a uni-sex approach like the commercial growers. Otherwise, you may end up with a pond full of 3 to 5 inch fish in the fall.
For a good discussion of pond culture of Tilapia and a uni-sex approach see the SRAC link below.
http://srac.tamu.edu/tmppdfs/9922301-280fs.pdf If you are interested in reading about the experiment I mentioned above see this link:
http://www.meadowlarkponds.com/fish.htm Good luck with them. They are really an interesting fish with great eating characteristics(as long as they are not eating algae themselves) and spectacular pond benefits, IMO.
