No.
That is one hard to answer question. I have seen 3 year old stock tanks on the side of a hill with no way for outside water to enter. Greenies by the dozen. I have no explanation. I looked and looked for the fish I thought I saw in my new pond and have never seen them again. I am not sure what I saw. It was muddy and windy with the wind trails you see on the water sometimes. I only saw a glimpse of something. Could have been anything. I retract my statement about a blue heron bringing some greenies into my pond. It is a complete mystery to me how isolated ponds always seem to end up with fish. It would be a fun experiment to build a small isolated pond and use a motion activated camera to record everything that happens, and see how long it would take for fish to appear.
