My goldfish "pond" (150 gallon Rubbermaid stocktank)
has lots of healthy plant growth so that should tide
the goldfish over for the winter. Pump is still running
and I'll let it run until we start to get freezes (assuming
that happens - it may or may not here).

I have goldfish babies I have to figure out something
to do with since the tank isn't big enough for 8 fish.
Three are pure black or charcoal, even one that is
about 1.5" long, after the time I would expect it to
show some color. I might move those to my inground
pond that's not filtered but has one goldfish that got
moved accidentally when I thought it was a minnow.

The minnow "pond" (110 gallon Toter stocktank)
is doing fine also, again with lots of plant growth.
This summer and last summer it had a resident
tree frog. I keep the water level close to the top and
I'm guessing the frogs find it easy to get in and out.

The stocktanks get covered overnight with wood
or siding when freezes are expected but uncovered
during the day. So far (just 2 years, so not enough
data for a trend) the only ice has been very thin
and I could pull that off.

The inground pond (200-300 gallons at a guess)
has minnows, one goldfish, and some quantity
of small green frogs. It too has tons of plants. It
hasn't frozen since it was put in place (about 3
years ago) but then it stays warmer due to
being sunken in the heavy clay soil (liner used).

All in all nothing exciting but the ponds are
pleasant to visit, easy to take care of.

Gail
near San Antonio TX Zone 8