Koi have equally as many enemies as they have admirers. Depending on what part of the world you live, these fish will have to face natural predators. Given the mature size these fish can easily be seen from the air, or with the flashy colors will be noticed from a distance. Add a waterfall and the sound will send the signal “fish dinner over here!”

There is no “one” way to safeguard the pond from all types of predatory pests. Some of these pests are also protected by law! Herons, for instance, are protected by international migratory bird laws. Ospreys are protected in New York. And so on. What is one to do? The answer to predation by birds is in the construction of the pond and by using clear monofilament fish line to deter attack.

I have used the monofilament line by stretching it back and forth across the pond, at different heights to make it more difficult for long-legged birds to maneuver, from 3’ beyond the water’s edge. In general, all that needs to be done is to make it easier for the bird to go elsewhere to find its next meal. They have excellent memories, some say “photographic” and can see ponds from the air, so will find their way back to your pond each year in their migratory flight. Since using the monofilament line I haven’t had to fight with the herons or egrets since!

Small predatory birds, such as kingfishers, will take more of a close-knit netting to surround the pond which may not be as attractive as the others, but this is an individual choice- koi or net? They are excellent fishing birds and can puncture what they can’t carry.

The next on the list of common pests would be the ubiquitous United States raccoon! This masked marauder is found everywhere and loves fish for dinner. A good sized koi can feed the whole raccoon family. When we build our ponds with sloping sides and bog areas in the pond in which the fish can swim, we are actually setting up “feeding stations” for raccoons, cats, wolves, bears, and other 4-legged fish-munchers. In this case, by constructing the pond with straight sides and planting or building next to the pond so they can’t get good footing at the pond, the fish have better protection. If all that fails, forget about motion-detecting sprayers. Get serious and install low-voltage electric fencing! It is reasonably priced and easy to install. Only turn it on when needed, like at night. These animals also have good memories. They say once a raccoon fishes in your pond you can never safely keep fish again. They will always return. But not if you can convince them it isn’t where they want to go. Give them something to remember other than the fish. Make it too expensive a meal!

I would never recommend shooting any predator that is fishing in my pond. I would probably have to repair the liner after I shot holes in it, even if the water didn’t deflect the bullets into my neighbor’s house or barn.

There is very little that can be done about predatory snakes if they are in your area. Other problems to watch for are otters, opossum, lizards, and whatever, but if they are native to your area, talk to others and find out what works for them. Trap the perpetrators, remove them, and pay to have someone else do it for you, or enclose your pond so nothing can reasonably enter. Bottom line is that we are building natural-looking environments and nature will come to call sooner or later. Build the pond deep, the walls high, and the covers strong!