Question
My pond fish have been hiding in a deep well for about a month.  Ten or more large goldfish are gone.  We suspect a heron in that occasionally see them but have not taken fish in the past.  The pond is deep and surrounded by tall trees.  Our neighbor's open pond is netted because of visiting heron.  We can too, but will fish come to feed and swim freely?

Answer
The idea is to just leave the net over the pond when you're not there.  It also helps to keep leaves out, too.  You could leave it in place permanently if you want to and it wouldn't adversely affect the fish.  In my experience, the act of a heron taking a fish from its pond can cause the other fish to hide for well over two months.

I hope this was helpful.