How do you stop blue heron from eating koi?

1. Cover Your Pond: Install netting, screen, or wire over the pond to keep herons from accessing it. Ensure that the covering is tightly secured and fastened.

2. Use Heron Decoys: Place imitation heron statues or decoys near the pond. Herons are territorial birds and will be less likely to approach a place with another "heron" present.

3. Motion-Activated Sprinklers: Install motion-activated sprinklers around the pond. The sudden burst of water will startle herons and deter them from staying in the area.

4. Visual Deterrents: Hang shiny CDs or holographic streamers near the pond. The reflections and bright colors can scare away herons.

5. Fishing Line Barrier: Stretch fishing lines or cords around the perimeter of the pond. The lines can obstruct the heron's view of the pond, making them less likely to land.

6. Predator Guards: Place pond covers with predator guards or spikes on top to prevent the heron from standing or walking on them.

7. Electric Fencing: Install electric fencing around the pond. The mild electrical shock they experience will discourage them from returning.

8. Guard Animals: Consider introducing a predator like an owl or hawk that preys on herons to naturally deter the herons from your property.

9. Sound Devices: Use devices that emit high-pitched sounds or distress calls of other birds to scare away herons.

10. Habitat Modification: Remove perches such as trees, rocks, or high ground that herons can use to survey and dive at the fish in the pond.

Remember that any changes you make to your pond should be safe and harmless to the koi residing in it. If you're concerned about the safety or well-being of your fish, it's recommended to consult with a wildlife management professional or a local wildlife control service for assistance in deterring blue herons and protecting your koi.