i have always wanted to do that! but, it would need a very large pond, imho. on that note, a neighbors jack russell used to take a dip in my small pond. the thought of it being lunch for a red tailed (not that i would know that happened) was a bit unnerving.
the water will have to stay warm. If the water was lower then the upper 60's I would be concerned about the red tail being able to make it. I better choice maybe a channel cat or a NA speices of catfish.
I remember seeing several in some man made creeks at Sea World in Orlando. One was over 4' long. They might bring them in over the winter months, I don't know.