I need to put in a goldfish pond and have been trying
to decide where is the best place for it.
NOT underneath your deciduous trees!! We have a goldfish pond that was abandoned when we bought the house. I cleaned it out and got it going again, only to learn why it had been abandoned the first time.
It's right on the edge of the forest. It's gorgeous when it's working, but it fills with leaves constantly. Then the leaves coat the pump. The pump overworks itself and burns out pretty quickly. It's a lot more work than I care to deal with - especially, since a lot of that work is freezing cold, wet, and slimy. Wet and slimy I'm fine with, but add freezing cold to the equation and I turn into a big baby.

If not for the leaves, I think it would be relatively low maintenence.