If there is a pond that flows into yours, that could easily be where the GSF are coming from. Theoretically, if he did not stock his pond there should not be any fish in it. But a kid or someone throwing in a few fish they caught someplace unbeknownst to the owner, thinking they are doing the pond owner a favor, is all it takes to get a pond full of GSF. Or his pond getting fish from a BOW above his pond.
If you can get permission, go fish the other pond and see what you catch. That would quickly tell you if your pond was "stocked" from his overflow.
Last edited by snrub; 10/12/14 12:23 PM.
