Carolyn, your pond looks beautiful!
I was only half kidding about the swimming part. We have plans for a bog filtered natural swimming pond, with fish. We have so many other projects on the list that we may never get to that one.
One year we had some bluegill get into our koi pond, probably brought in by ducks when they were eggs or fry. we were able to net them out, and I kept them in a large fish tank for another 2 years. They were really beautiful, and easier to keep than any aquarium fish I had ever raised.
The water lily in your photo sure looks healthy. Do you keep tropical lilies also?