Koi Predators

After you have completed your koi pond, your fish become part of the local food chain. Unfortunately, that means they are on the menu for local predators. If you’re expecting harmony, you are setting yourself up for disappointment.
“Know thy lot, know thine enemies, know thyself.” ~ Sun Tzu, The Art of War
It’s important to remember that, while we may not like that our koi are open for attack, predators are just following the laws of nature. Whether you’re in the middle of an urban community or out in the country, you’ll run into your share of wild animals, all of whom are looking to survive.

You can minimize your fish loss in most circumstances when you take predators into consideration during the design phase. Remember that fish are low on the food chain and are a potential meal for many of the animals in the vicinity. Your beautiful koi look like a delicious dinner to cats, turtles, frogs, raccoons, weasels, and birds such as herons and hawks.

It’s important to note that, once a predator has identified your pond as a feeding ground, you need to deal with this very real problem.

Minor Predators


While cats probably aren’t going to target your koi, they may scratch or nab a fish on occasion. Tame fish are more at risk.


They may be slow, but turtles are smart when it comes to finding food. Although not common in urban centers, if turtles are about, they will ambush and eat fish, one of their favorite treats. Preventative measures include a raised edge around the ponds or natural large rocks and stones at the pond edge to prevent turtles from walking into the pond.


Frogs are not particular with their diet and your koi are easy for them to catch and eat. Female frogs can weigh up to two pounds and be 18 inches long, a size that enables them to capture larger prey.

Serious Threats


The depth of your pond will affect how much of an impact raccoons have. In a deep pond, they are a minimal threat, but in shallow ponds, they can be deadly. These nocturnal predators are intelligent, omnivorous, and hungry. A large male can weigh more than 50 pounds, so they can easily capture one of your larger pond dwellers. To prevent racoons from stealing your koi, the pond should be raised approximately 18 inches off the ground, and the water level should be down 12-inches from the pond’s edge.

Luckily for you, raccoons are looking for a low barrier to entry. If your pond has deep water and no wade-in entry point, they will likely move along. Sections deeper than four feet pretty much guarantee safety from raccoons, although you’ll still want to keep an eye out for these pesky critters.


Herons are fish eaters; it’s in their genes to prefer them. The great blue heron is the largest variety in North America with a wingspan of seven feet and standing four feet tall. Because of their size, herons are unable to land and hunt in smaller ponds. If a heron has targeted your pond, you’ll need to take immediate action. These birds will travel 30-miles to search for food. Once they’ve found it, they’ll be back. To prevent heron from gaining access to your pond, you need a raised edge or put a string line back a foot from the edge to prevent heron from walking into the pond, and the water level should be down 12-inches from the pond’s edge. There should be no ledges on the outside of the pond which would allow the heron to stand in the pond allowing him deeper reaches into it. Submerged into a deep place of the pond, you could put a shelter that is easily checked by you, where the koi can hide from predators.

Minks and Weasels

Weasels are semi-aquatic predators, voracious eaters, and very dangerous to fish. They are bold, intelligent and aren’t likely to be scared off by humans. Even a net won’t stop the mink, so you will need to outwit them.

Usually, minks are territorial and solitary, although there have been cases of nearly half a dozen visiting the same pond. Koi can often evade weasels during the warmer summer months, but when they slow down in the fall, they become easy prey.

An Electric Fence May Be the Answer

For persistent prey, such as minks, clients have seen a 90% success rate in protecting koi by using electric fences. An easy installation project for most DIY keepers, the fence is set up like a trip line so the animal cannot just jump over it.

If you want to discuss threats and solutions for your koi pond, contact us today. We’re ready to help.