Herons

HI,
We have had a successful, small (100 gallon), garden pond for some years.
We have lost some fish to raccoons, but with fishing line across pond to
deter herons, and a petstore electric fence to ward off raccoons, have
recently done well.
HOWEVER after a bird commotion today, we looked to see a heron standing by
the pond, and fish were taken although it flew off.- we are not sure how
many, as the remainder are spooked and hiding.
I know you can buy "fake" herons at an aquarium store, and am enquiring if
herons are territorial, and this ploy would work?
I would certainly be interested in any other helpful tips anyone could
offer.
Thanks a lot, Tony