Ponds are like having a swimming pool when its time to sell the house.
Its not really a selling point, for some its a hassle.

In the same respect as if the new homeowner wants it, then it had value,
if they don't want it then doesn't. My neighbor was selling his house
and one buyer wanted him to remove his 9K gallon pond. This is where I
got a lot of my lighting, pumps, plants, Filters ect.. The sad thing is
the buyer backed out of the deal, the pond is still there and I have all
his equipment.