Koi ponds naturally attract wildlife to your garden, which can provide a rich oasis for animals in addition to your fish. However, the welfare of your koi and goldfish must be your top priority, so it is important to know which species to welcome and which to deter.
The following are probable creatures you might encounter as they try to live rent free in spaces in or around your pond.
Birds
Some birds make wonderful additions to a pond environment, while others are the worst predators around. The key is to attract the birds you want while deterring the dangerous ones. Species such as herons, kingfishers, and cormorants are capable of killing your entire koi population in a single sitting.
You can make the area around the pond friendly for desired birds, like blackbirds and other songbirds. Plant trees and shrubs near the pond to provide nesting and shelter. Place seed feeders near the pond and add perches overlooking the water.
Netting is the ultimate defense against fish-eating birds. Small songbirds are able to drink through the netting but large birds cannot access the fish. It also is effective for catching leaves and other debris in the fall.
You can further deter predatory birds by adding decoys around the pond. Most predators are territorial, and the presence of a decoy will trick them into thinking the territory has already been claimed.
Additionally, provide pond structures, such as rock ledges, that offer safe hiding places for your koi.
Geese
Canada Geese are the most commonly encountered goose variety for pond owners. Though these waterfowl predominantly inhabit lakes and rivers, they won’t pass up a larger backyard koi pond if there’s food present.
One problem with this is that both your shallow and submerged pond plants are on their menu. Another is the excessive amounts of waste geese produce–up to two pounds each day, much of which is tossed into the water when they fly. The excess phosphorus and nitrogen adds more nutrients to pond water than most koi ponds can handle, especially when the geese have depleted your biological filtration.
Therefore, though geese can be pretty, they aren’t great additions to a koi pond unless you want to spend hours each day cleaning their mess and keeping them away from your plants. Getting rid of geese isn’t too hard–you just need to create loud noises to scare them off. The bigger issue is preventing their return, which you can do using liquid goose deterrent and decoys. Never feed the geese, as this will almost ensure that they stick around.
Ducks
Ducks are beautiful creatures to have in or around your pond, but they also will destroy every plant you own in record time. They will spare no variety–floating plants will get shredded, submerged plants uprooted, and marginal plants trampled.
While they aren’t a threat to your koi, like geese, they produce an enormity of waste. Most filtration systems are not up to the task of dealing with a group of ducks (they tend to travel in teams). They also will steal floating fish food from your koi.
The easiest way to ward off ducks is to install pond netting and set up decoys. Most importantly, you must resist the urge to feed them.
Dragonflies
Most people find dragonflies to be among the more attractive insect species, and your pond can provide them with a place to lay their eggs. Dragonflies also feast on other less desirable insects like flies and mosquitoes.
Multiple species of dragonflies exist and some require a specific plant stem for egg laying. Some dragonflies prefer the leaves of water lilies while others prefer the stems of lotus flowers. Still others prefer laying their eggs on submerged wood. You will need to research what dragonfly species are native to your area and install the right vegetation to attract them.
If you don’t want dragonflies, there isn’t much you need to do. If you don’t set up your pond to help them survive, the koi will eat the larvae before they hatch.
Snakes
Water and garter snakes are the types that most people will encounter near their ponds, and they are completely harmless. These snakes also have the potential to assist in the health of your pond’s ecosystem, keeping populations of smaller critters under control.
Most snake species that are found near water won’t attempt to feed on koi or goldfish. However, some will occasionally eat koi eggs and fry, as well as small goldfish. Therefore, they can pose some risk if you own a breeding pond, but, otherwise, they add balance to your little slice of nature.
However, not all pond enthusiasts (or people in general) are fans of snakes. One of the most effective ways to keep them away is to remove any spots they might use for shelter or as a hiding place. Another is to add snake-repellant plants to your yard, such as lemon grass, marigold, wormwood, and garlic.
Frogs
Many koi owners enjoy the occasional frog in their pond. Frogs can effectively keep the pond insect free, with the ability to consume up to 10,000 bugs in one summer season. They also clean the pond by eating excess algae and organic materials.
Most frog species are compatible with koi, with the possible exception of bullfrogs. Bullfrogs will eat anything they can fit in their mouths, including fish eggs and baby koi and goldfish. However, like snakes, they only pose a problem during breeding season.
You can make your pond frog friendly by adding lush grasses in and around it. Provide areas with slow water flow, as well as plenty of shelter. On the other hand, if you want to keep frogs out of your pond, you can sprinkle coffee grounds around the perimeter or spray with a mixture of water and vinegar or peppermint oil.
Toads
Toads will most often invite themselves to your pond space in the spring, as they use the environment for mating. Their range is mostly eastern North America and eastern Canada. Toads will eat anything that can fit in their small mouths, so some pond enthusiasts welcome them as free pest control.
Typically, your koi will keep toad populations in check. However, in some cases toads can overpopulate and you might want to manually keep them out. You can catch the toads in a net or pond skimmer, relocate them, and prevent their return by installing fencing too narrow for them to squeeze through. Just make it deep enough that they cannot burrow beneath it.
Moles
Moles build their nests near water sources because this is where they find most of their food. Their homes consist of tunnels underground, which can be up to 20 feet deep.
Though these burrowing land mammals prefer to stay dry, they are relatively good swimmers. They will feast on everything edible in your pond (though they are much too small to harm your koi).
A common sign that moles are present is a sudden drop in the water level as they chew through the pond liner. Garlic extract, castor oil, and chili pepper flakes are some of the best repellents to use. However, you have to first locate their tunnel entrances. Form a half-moon shaped “barrier” of extract-drenched soil on the opposite side of the direction you want them to move.
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