Comets, just like shubunkins and other pond goldies, adapt really well to the weather outside, when done GRADUALLY. Since your fish comes most likely from a heated invironment, I would wait until the temperature outside is warmer. Once outside, going through summer and fall, he can adapt to pond temperatures, as long as they dont drop too low, and you might be able to keep him in that pond next winter. But for now, let him enjoy his *spa* treatment!