Whether you want them or not, having frogs in koi ponds is normal. Frogs just love adopting ponds as their homes. If you have a koi pond in your yard, chances are that eventually some frogs are bound to show up. The same types of features that make koi ponds so beautiful from an aesthetic point of view also create oases for local wildlife.
Is a frog in a koi pond a benefit or a threat? Most frogs are harmless to koi. However, some very large types of frogs can try to eat smaller koi, while big koi have been known to eat pond frogs, tadpoles, and frog eggs. For the most part, the two animals are compatible in the koi pond, with frogs acting as a good barometer for overall koi pond health.
There are a few threats associated with keeping frogs in your koi pond, but the benefits far outweigh the risks. Keep reading to find out more about how frogs influence your koi pond and why you should see residential frogs as a good thing.
Frogs Are in Ecological Danger
Rather than being a threat, the truth is that most species of frogs are under ecological threat instead. There have been a number of factors negatively impacting frog populations across the globe, including the following:
- Habitat loss
- Human encroachment
- Widespread use of pesticides
- Invasive species that out-compete them for resources
In many cases, people start an outdoor koi pond or similar yard project because they feel a need to beautify and diversify their outdoor environment. Biodiversity needs to be actively maintained in wildlife populations that are under threat. Giving shelter to frogs via a koi pond can help preserve the overall ecosystem of your local area, so it’s an environmentally responsible thing to do if you can swing it.
Frogs Are a Sign of Environmental Health
Along with helping to maintain a healthy ecosystem, frogs are also a good thing to see in your koi carp pond because they are sort of an environmental canary in the mineshaft—if your pond is able to support local environmentally sensitive wildlife such as frogs, that means that the koi pond is operating well on an ecological level—frogs cannot survive in ponds where the water chemistry is off, for example.
When frogs move into your backyard koi pond, that means that you have achieved a certain level of homeostasis in your pond system that closely mimics the natural homeostasis of a wild environment. This is a sign that your koi pond is flourishing, so if you see frogs in your pond a few weeks or months after getting it set up, pat yourself on the back!
Along with being a good barometer of pond health, frogs also provide a service by helping to cut down on insects such as mosquitoes and other pests. This can be a major boon for koi pond owners who are also gardeners since frogs can eat up to a hundred insects in a sitting.
Larger Koi Can Kill Pond Frogs
Pond frogs don’t present much of a threat to larger koi because, in a lot of cases, the opposite is true—if anything, large koi will be inclined to eat frogs, tadpoles, and frog eggs. Like goldfish and other fish in the carp family, koi are notorious for trying to eat anything they can fit in their mouth, including frogs.
With large koi in your pond, it’s next to impossible to keep koi from eating frogs if they manage to catch them. After all, you can’t monitor the koi constantly. The only way to prevent the behavior is to try and keep frogs out of your pond and make sure the fish are well fed so they aren’t as tempted to hunt.
If you’re wanting to introduce frogs to your pond and you already have large koi, it’s not a good idea to purchase captive frogs to introduce to the pond in case the fish decide they want to eat them. Instead, let wild frogs move into the pond of their own free will. Wild frogs are more “pond-smart” than captive frogs and can evade predators like large koi more easily than their captive cousins.
Large Frogs Can Kill Small Koi
While most species of pond frog will not hurt koi deliberately, large frogs such as American bullfrogs are opportunistic predators. This means they will eat and catch small koi or other fish if they can manage it. Frogs can also inadvertently kill koi if a koi fish tries to eat one and chokes on it.
This isn’t a common enough occurrence to actively try and look out for it, but if you’re worried about your smaller koi after a big bullfrog decides to move in, you can always remove the frog from the pond to help protect them. Generally speaking, the larger a frog is, the easier it is to catch and relocate if you need to.
In most cases, it isn’t worth trying to relocate a large frog on the off chance it kills one of the koi since frogs will usually go after fish that are already weak or sick. Most of the time, a frog won’t bother with prey that large unless it is an absolute whopper.
How to Attract Frogs to Your Koi Pond
Want to attract frogs to your koi pond? There are a few ways you can change up your koi pond design to make it more tempting for frogs to visit and move in. Here are some things you can do to make your koi pond a good habitat for local frogs:
- Make sure any water features in the koi pond are slow-moving. Waterfalls and other turbulent water features cause the currents in the pond to be too swift to be attractive for frogs, who prefer calmer waters.
- Provide shelter. One easy way to give frogs some shelter around the outskirts of your pond is to bury pots halfway into the earth around the pond’s edge, leaving a lip overhang that frogs can crawl up under. Small pots can also be placed upside down and a small hole created in the edge of the pot where it meets the earth to give frogs a space to climb in and hide.
- Plant plenty of pond plants—aquatic and marginal. Marginal plants situated around the edge of the koi pond (such as tall grasses) provide plenty of cover for frogs to avoid predators. Frogs will avoid any open spaces which leave them exposed. Plants inside the pond itself provide oxygen not only to your koi but to frogs as well.
Wild frogs can be easily encouraged to visit a koi pond with just a few attractions since it is difficult for them to find suitable habitat in urban environments. So for those koi pond owners who want frogs to inhabit their pond, it doesn’t take much effort to tempt the little guys in.
How to Remove Frogs from Your Koi Pond
You always have the option to remove frogs from your koi pond and take them to a more suitable location. It is kind to relocate frogs to another body of water since they are aquatic and must have a source of water to survive. If you relocate a frog in an area with no water, it will either die trying to find water or will end up in someone’s swimming pool skimmer.
Here are some tips on how you can catch frogs to remove them from your koi pond:
- Go frog hunting at night. Frogs are most active in the evening when they can hunt under cover of darkness with less threat of predators, so that’s the best time to catch them. Be sure to get a brightly-lit flashlight so that you can shine it along the pond’s edge. Like the eyes of other animals, a frog’s eyes will shine in the light, allowing you to easily locate them.
- Frogs are best caught with a soft landing net. Frogs are fragile creatures and it is easy to accidentally crush and injure them if you try to grab them with your bare hands. You should avoid touching a frog with your bare hands whenever possible to avoid damaging the frog’s delicate skin. Wild frogs are also easily shocked by human contact.
- Put the frog in a covered bucket and relocate to a different body of water. Make sure that the bucket has holes in the lid to prevent the frog from suffocating before release. It’s also important to make sure that the bucket wasn’t previously used to transport cleaners or other chemicals since frogs are very sensitive to chemical contaminants.
If you do end up with frogs in your pond, you can always remove them before they have the chance to reproduce. Just be respectful and make sure not to injure or kill frogs in the process of removing them since their populations are already under environmental threat.
How to Keep Frogs Out of Your Koi Pond
When you’re still in the planning stages of building your koi pond, you can design the pond to cause frogs to avoid it if it’s not an issue you want to deal with. To prevent frogs and other wildlife from being attracted to your koi pond, take the following steps to make the koi pond inhospitable to wildlife:
- Install water features that increase circulation in the koi pond. Koi usually don’t mind a little extra turbulence in the pond water, but frogs don’t like it and will avoid any source of water where there is a strong current.
- Remove any marginal plants, rocks, and other shelters that might act as hiding places for frogs on the outskirts of the koi pond. While this may make your koi pond appear more austere, this will deter frogs and other wildlife from approaching the pond, since wildlife tends to avoid environments that expose them to predators.
- Leave any outdoor lighting off at night except when the area is being used. Outdoor lighting attracts insects such as moths and flies that in turn attract frogs and other wildlife that likes to prey on them.
- Don’t leave pet food out at night. Many forms of wildlife, frogs included, are attracted to the smell of pet food that is left out overnight.
- Install silt fencing. Silt fencing that is buried around the perimeter of the water’s edge deters frogs from going in or out of the pond.
Frog Care in Fall and Winter Koi Ponds
Frogs that live in your koi pond go into hibernation over the winter months. In a frog’s hibernation, it will go into a coma-like state and its heart will even stop beating. Frogs hibernate on the bottom of the koi pond and breathe through their skin, surviving on oxygenation from the surrounding plants. Here are some ways that you can help your froggy friends in the koi pond survive the winter comfortably:
- Make sure that your pond filter is covered (frogs may attempt to hibernate inside it otherwise).
- Make sure that your pond plants remain healthy throughout the winter months so that hibernating frogs (and fish) can remain oxygenated throughout the coldest months of the year, when the top of the water may freeze over.
- If the water over the koi pond does freeze, create a hole in the ice so that frogs can escape and there is better oxygen exchange with the water below. A hole should be created by pouring warm water rather than using a tool, as this can injure sleeping fish and frogs beneath the surface of the ice.
- Create alternate hibernating places around the koi pond for frogs to use—they will also hibernate in moist leaf piles and wet, rocky dirt.
Providing a safe, comfortable place for both koi and frogs to snooze the winter away is one of the most important services during the year that you can provide to your aquatic friends.
Koi Pond Frogs vs. Koi Pond Toads
The same steps you take to attract frogs to your koi pond are also likely to attract another type of local wildlife—the common toad. Toads are similar to frogs except that they are only semi-aquatic and survive primarily on land, while frogs are primarily aquatic and only spend part of their time on land.
While both frogs and toads are a good indicator of pond health, frogs are generally harmless to koi. Toads, on the other hand, are often toxic and this toxin can kill smaller koi. Their eggs are also toxic to koi and can kill them if ingested.
Toads are often mistaken for frogs, but there is one easy way to remember how to tell the two amphibians apart—toads have a bumpy textured skin more reminiscent of a lizard than an aquatic animal, while frog skin is smooth like a fish.
Like frogs around koi ponds, toads are an indicator of the health of the local ecosystem—seeing them is a good thing. And like frogs, these friendly guys also help rid your yard of insect pests that damage your vegetables and flowers. So even if you don’t want frogs or toads around your koi pond, be kind and relocate them somewhere safe to help maintain biodiversity in urban environments.
Toad Eggs vs. Frog Eggs
You may come out to your koi pond and find that it is full of eggs. These eggs are likely to be one of two things—frog eggs, or toad eggs. Toad eggs can be distinguished from frog eggs by appearance—most toad eggs are black and stringy-looking, while frog eggs are translucent and are usually laid in a gelatinous mass.
Koi will usually eat or ignore frog eggs, but if toad eggs are found in the koi pond, they should be removed to avoid poisoning the fish.
In either case, it can sometimes be an advantage to remove frog and toad eggs from the koi pond, especially smaller ponds. This is because huge swarms of tadpoles can put a large burden on the pond’s ecosystem if the pond is small—their numbers can cause a decrease in dissolved oxygen in the water as well as a spike in the ammonia in the water. This sharp shift can cause weaker koi to sicken and die.
Some tadpoles and frog eggs are not a cause for concern in a pond, but if you find your pond infested with tadpoles, it’s a good idea to remove the majority of them to a larger body of water where they have a better chance of survival and aren’t taxing your koi pond’s ecosystem.
There Are Some Risks to Koi Pond Frogs, but the Benefits Outweigh Them
There are a few risks involved in keeping frogs in your koi pond, but most of the risks discussed above aren’t a serious threat to your koi, and the advantages of allowing frogs to populate your koi pond far outweigh the risks associated with them.
Not only do frogs act as an indicator of good koi pond health, but they also add beautiful sound, activity, and colorful diversity to your pond environment. Add a few small design elements to help encourage wildlife to use your pond, and you’ll be entertaining choirs of frogs for seasons to come.