Ryan,

It depends....

I have some available space in an old chicken house and also in a tractor shed. Either could be insulated/enclosed for a fish holding tank....and either could be augmented with propane or electric heat.

Our winters are mild in East Texas. Lows below 32 degrees are very rare and even cold nights are always followed by warm days (almost always).

I would consider a green house for this application but would prefer to utilize existing space if possible. Thanks for your interest.