Do Frogs Harm Koi? (Solved & Explained!)

If you’re planning on building a pond in your backyard, then you need to make sure that the ecosystem is protected. Having fish in your pond, like Koi, can bring beautiful color and life to your pond.

Yet you may be worried about the eventual appearance of frogs. Are those fears founded in truth? Large frogs like bullfrogs can eat baby koi or koi eggs. They will not harm adult koi though. Small Frogs and koi can live happily together and even keep each other in check by eating each other’s eggs.

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Do Bullfrogs and Other Frogs Eat Koi Fish?

Large frogs like bullfrogs can eat baby koi or koi eggs. They will not harm adult koi though. Frogs and koi can live happily together and even keep each other in check by eating each other’s eggs.

Do Koi Eat Frogs, Tadpoles, or Their Eggs?

One problem you may face is your Koi eating their frog neighbors. Koi do eat smaller frogs, tadpoles, and frog eggs.

While it’s not their preferred food, they will eat them given the opportunity and lack of other food sources. Since the skin of frogs can be toxic, you may worry about what this might do to your Koi.

Luckily, Koi don’t seem to suffer any adverse effects after eating frogs. If you want to keep your Koi from eating fish, then research seems to suggest that introducing larger frogs is your best bet.

Bullfrogs and other larger frog species are too large for the Koi to eat. You’ll still have problems with them eating tadpoles, however.

Are Frogs Bad For A Pond?

Like any minute ecosystem, it’s easy for things to become unbalanced. A frog can help balance it.

This is because frogs are not afraid to eat each other’s eggs. This keeps the population of frogs limited.

They can also eat other kinds of bugs and pests that may injure or make your Koi sick. Smaller frogs may even serve as a fine meal for your Koi.

If you don’t like frogs, then you might consider them bad. Otherwise, frogs can offer pleasant sounds and wonderful colors to your pond.

How Do I Keep Frogs Out Of My Koi Pond

The easiest way to remove bullfrogs that are eating your koi is by catching them manually and then either taking them off-site (or killing them).

Do this with a headlamp and a net or frog spear at night.

We recommend this headlamp and this frog net.

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South Bend Frog Spear, 4 Tine
You can also use a frog spear like this one. Click the image to see on Amazon. You’ll need to screw it onto a wooden dowel. The downside is it won’t kill the frog just injure it and you’ll have to manually kill it later which is why we prefer the net. With the net you can capture them, put them in a bucket, and take them far from your property (or kill and eat them like we used to do back in Virginia).

Watch this video on how to capture bullfrogs.

The bad aspect of frogs is that they always find their way to the water. No one quite understands how a frog has this keen ability, but if you have a pond, then chances are you’re going to have frogs, too.

Frogs like to burrow under the ground, too, so erecting any kind of fence around the pond isn’t going to help you very much.

Instead of using chemicals, which can also harm your fish, you’ll want to make the environment unpleasant for frogs. This includes introducing a waterfall or some kind of fountain that disrupts the water.

You’ll also want to remove tall grasses. These act like a cover for frogs to hide from predators.

Does Salt Kill Frogs?

If you would prefer to kill the frogs in your pond rather than relocating them, then you’ll want to make a mixture of salt and water. Spray this mixture directly onto the frog or in the area where they frequently rest.

The salt will dehydrate them and make them die.

What Kills Frogs Instantly?

Going after their food source can kill frogs. Spraying mosquitoes and other bugs with a chemical repellent will also kill the frog after it consumes them.

You can also use certain chemicals to kill frogs, themselves.

You can also introduce natural predators. Snakes and cats love to kill and eat frogs (but also fish).

Finally, you may want to try natural methods like spraying them with citric acid or caffeine. Caffeine, in particular, will cause them to have heart attacks.

Again, don’t worry about small frogs. They won’t harm your koi. Only spend your time getting rid of big bullfrogs using the methods above.

What Eats Frogs In A Pond?

If you prefer the natural predator method, then you’re going to want to allow snakes to enter your pond. They love eating frogs.

If you have a pet cat, then you can also let them roam around the pond. Your Koi may also be able to help you with your frog problem if they’re a smaller species of frog.

Finally, certain birds like geese and ducks love eating fish. Allowing them to settle in your pond may give them the chance to eat the frogs.

List Of Frogs That Can Live With Koi

Here are a few frogs that co-exist peacefully with Koi:

  • Bullfrogs
  • Northern leopard frog
  • Wood frog
  • Pickerel frog

You should also search for your native frog species and choose the largest of the species from that list.

How Do I Stop Them From Fighting?

If for some reason your Koi and frogs are fighting, then you’ll want to keep them separated. The best way to do this is by creating two areas in your pond.

One should be for the fish and include a waterfall or fountain to keep the frogs away from it. The other should be a still pool of water with lots of grasses to make the area suitable for frogs.

What Should I Feed Them?

Frogs love to eat bugs. You can also feed them small crickets and other small insects.

Otherwise, they can take care of themselves.

How Often To Feed Them

Young frogs typically need to be fed five crickets twice a day, according to research. Older frogs only need to be fed once a day or every other day.

How Long and Deep Should the Pond Be?

To make your pond suitable for frogs, you’ll want to have a relatively large pond. In particular, ponds are suggested to be eighteen feet long and twelve feet wide.

Ponds also need to be deep enough to avoid falling prey to the freeze line. This is around 1.5 meters deep.

Helping Your Frogs and Koi Through Winter

Frogs, in particular, go into a stage of hibernation during the winter. To ensure both your Koi and frogs make it through the winter safely, there are a few things you can do.

The first, for frogs, is to give them plenty of places to burrow. You can add small piles of leaves and other vegetation for them to hibernate beneath.

They’ll also hibernate at the bottom of the pond with Koi. To ensure your Koi and frogs have enough oxygen, you’ll want to regularly make a hole in the ice.

This allows oxygen to pass through the ice. It also allows your frogs to hop out.