unclenedsfishfactory.com

fish pond predators

There is nothing more frustrating than having your pet fish eaten by a Great Blue Heron or other wild animal.
Some suggestions I've heard of are listed below.

design the pond to be very steep & very deep

put in large pipes or other cover for the fish to hide in

surround the pond with a string or fishline trip wire with noisy bells

get a "scarecrow" with an electric eye that hooks up to a garden hose that will squirt water when the beam is broken
(possibly an electric eye with flashing lights will work too)

let a big dog out early at dawn and also at dusk

put out wolf urine, supposedly animals can smell this and they stay away