Al you have a tilapia. If you saved it and put it in 50F water in the refrigerator or cool water & it promptly died - tilapia positively. It will not survive your winters. Someone stocked your pond.
I didn't think Acara got that big. We had a few Blue Acara in our 75 gallon tank and they were the bosses. Just about killed everything smaller and everything bigger had their fins nipped off.