16 seems like way too many, considering i am only raising it a few degrees and only a few times per year. I will look into it though. Someone said that they kept them outside all winter without heating is South Lousiana, which i beleive has similar low temps to here. They might be okay, i think.
Also, what water conditions are they found in in the wild (pH, hardness?). My water has a pH of around 7.8 and medium hardness. I think that captive bred ones would actually be hardier, as they do not have to adjust to captivity. Does this make sense? I would prefer captive bred ones if possible.