A week or so ago, I noticed a pretty big goldie swimming around in the VF.
It was in the upper pond which tells me, it took a ride through the pump, so
it must have been very small when it arrived. It's now about 4 inches long.
Anyway, we rescued him/her yesterday as that part of the VF freezes solid
every year. When we brought him in he was distinctly black colored, as he
swam around in my SO's salad spinner. After letting the water warm a bit, I
dumped him into the aquarium. I noticed however over a few hours he changed
from distinctly black to a golden color.

I don't know if he is a goldie, koi or koidlie as he seems to have features
of all three. Either way, do goldies, koi or donkey koi/goldies change color
over hours?

BV.