Keeping your koi fish pond safe from predators requires some planning on your part. However, you should be able to deter any predator that might be interested in your koi.
The wrong kind of bacteria is deadly to koi. Install a good mechanical and a biological filter in your pond to keep the fish safe from parasites and diseases like fin rot and ulcers.
Encourage healthy bacteria by planting natural bacterial sponges like Anacharis plants.
To deter predators from the shore, purchase floating 3/8 inch mesh. It fastens around the pond and is made of UV resistant black polypropylene. When in place, the mesh is nearly invisible. However, animals from the outside are unable to reach through it to capture the koi.
A great way to keep your koi fish pond safe is to add “koi houses” to the pond. These sturdy, mesh cages sit on the bottom of the pond. If koi see a predator approach, they swim into the cages and have a bit of protection.
Some pond owners prefer an electric fence around their pond. However, this can be dangerous to children and ineffective against birds of prey.
A homemade or purchased scarecrow can be effective against birds. It may not be effective against animals, however, once they get used to the scarecrow.