29 gallon Tub pond?

[Liz Sagara]

I want to do an above ground tub pond. I don't want to close it in anything just put it on the back porch and paint three of the sides to make it look better. Then I was thinking of putting a couple fancy Goldfish in it during the summer. or maybe a Betta. Dunno. What would be the best way to do this? should I put a little heater in there to kick on if it goes below 60?