I brought in my deck pond shubunkins, they don't get heated water. It sits around 72-75. I had a heater, twice, quit working i.e. on and off control, stayed on and cooked my fish (ciclids in arizona) So I would rather not use a heater. They have it better than the pond fish..........burr water dropped to 46 with the storm. It was 63 right before sandy hit.
Nice looking inside fish you have there! They will be nice and toasty for the winter.