I got my Tilapia from Todd Overton at
http://www.overtonfisheries.com , close to Centerville between Houston and Dallas. He runs a really nice fish farm there. I just bought 20, to see if they make it through the winter. I am thinking about making an insulated box about a yard cube and using solar water heater to pump warm water in it during the day. But, the time is in short supply and there are more pressing projects before winter arrives...