That grey suited bird visits us, we have wind propelled spinners, gaurdy dragon flies & cotton up to thrawt him.
Fake herons don't work, heron's are social birds & live in heronries, another heron is showing there is good fishing to be had at your pond.
Last time he raided, he took a 8" gold tench, spiked a 10" orf to death & emptied the pond.
Only the 16" ghost carp escaped, at 2lb, that would have been a meal.
If nets are fitted close to the water, he may still try striking the fish, if he spikes them, it will kill them, the net just stops him eating the body.