With patience and excellent stalking abilities, herons can still eat some of your fish despite your best defenses. The best answer to solving a winged predator problem is to incorporate a water sprinkler with a motion detector attached. These are readily available in the marketplace and designed to handle predators such as herons. The sprinkler is hooked up to the water spigot on the house, and installed alongside the pond. When the predator nears the pond the motion detector is triggered, sending a quick burst of water in a general direction, scaring off the unwanted visitor.
Herons are far and away the biggest predator on ponds.
Still less than 10 percent of our customers lose fish to herons. To worry about an occasional heron does not justify not installing a pond. There are many other predators that occasionally dine on small fish. Large bullfrogs, snakes, and even turtles may occasionally catch a meal from time to time. Just chalk it up to nature.