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Frogs are common visitors to garden ponds, water gardens, and backyard ecosystems across North America. Whether you're managing a koi pond or a natural wildlife habitat, understanding what frogs eat helps maintain balance. Frogs can be a large indicator of water quality, and complement (and control) the biodiversity of ponds of all sizes.
But what exactly do frogs eat in a pond? And is it safe to keep them with your fish?
Let’s hop in, shall we?
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Frogs are carnivorous, which means they primarily eat other animals, usually small, live ones. Their diet depends on their size and species, but pond frogs typically eat:
Insects (flies, mosquitoes, beetles, etc.)
Worms
Spiders
Snails
Slugs
Small fish
Tadpoles (including their species)
Aquatic invertebrates
I’ve even seen a bullfrog eat a small snake once
Some frogs, like the green frog or leopard frog, hunt near the water’s edge, while others, like water frogs, may hunt underwater. They rely on quick reflexes and sticky tongues to snatch prey. Frogs (and their less moist cousins, toads) can sit and wait for nearly anything that can fit in their mouths to wander by then, SLURP - down the hatch it goes.
Yes, frogs do eat small fish, especially if the fish fit easily into their mouths. This includes tiny minnows, mosquito fish, and occasionally even young goldfish or koi fry. This is pretty rare for the most common amphibian denizens of our aquatic habitats, but it can happen. Most frog species are more than happy to munch on insects and squiggly critters as fish are quite quick and difficult to ambush.
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Larger frogs, like bullfrogs, are more aggressive. They have powerful jaws and have been known to eat:
Goldfish
Small koi
Minnows
Even other frogs or small birds
If your pond is home to small fish or baby koi, it's smart to keep an eye on frog activity. Abundant frogs can also lure in other predators like herons and mink, which will gladly stick around and sample your fish.
It’s possible to keep frogs and fish together in the same pond, especially if you create the right balance.
Tips to help both thrive:
Creating a habitat/ecosystem relies heavily on mimicking natural waterways (streams, lakes, wetlands, etc)
Provide hiding spots for small fish using aquatic plants or decorative rock caves.
Natural habitats rarely sport straight lines or smooth surfaces. Break up your pond using stone, plants, and large woody debris like stumps. This lends a natural quality to your water feature AND provides habitat for all sorts of pond’s edge creatures.
Choose larger koi or goldfish that won’t fit in a frog’s mouth.
Most fish species (including koi and goldfish) are large enough, after their 1st summer in the watery depths, to coexist with all but the largest frog specimens
Any fish 3-4in or larger should be safe from frogs
Avoid introducing bullfrogs, as they’re known to dominate and disturb other pond life.
These are our largest, meanest frog species. I think I saw one with a cigarette
and a Bowie knife once…
Keep pond depth varied, shallow edges for frogs, deeper zones for fish.
This varied habitat also breeds a more diverse pond ecosystem, which is always good.
Most green frogs and leopard frogs coexist peacefully with pond fish, especially in natural-style garden ponds.
Learn more about our common frogs here:
Common Frogs and the Toad of the Midwest … Water Quality and Diversity in Small Ponds
Frogs prefer live prey, and in a pond environment, their favorite meals include:
Mosquito larvae and adults: Frogs help reduce mosquito populations naturally.
Swimming aquatic insects, like water beetles or larvae.
Aquatic bugs and invertebrates: Like dragonfly nymphs, scuds, and water striders.
Occasionally, frogs might nibble on aquatic plants or phytoplankton, but this is rare and not a major part of their diet.
Well, kind of. Any species, when they are allowed to completely dominate a habitat, can cause damage or at the very least, create an annoyance. Copious frogs can be pretty loud when they are in breeding season, so a pond with a thousand frogs can put up a fair racket….
Like most other denizens of the greater outdoors, Mother Nature keeps their numbers in check, but if your pond just has too many frogs, I suggest:
Stocking a few (or one) largemouth (or smallmouth) bass.
Natural predators for tadpoles and adults - bass will easily control amphibian populations
Careful, as bass will also gobble up young koi and goldfish too
Before stocking a predator, be sure your resident fish are big enough to NOT be prey for the specimens you are introducing.
Rule of thumb: it takes a 16-inch bass to eat a 3-4 inch goldfish.
If the bass start threatening your other fish, you can simply fish them out and remove them from the pond. Replace them with a smaller one to control the frog species in your area.
Stocking numbers will depend on the size of your pond - for backyard koi ponds, one bass is plenty
Stock a handful of sunfish or crappies.
Larger sunfish (bluegills, pumpkinseed, black crappie) will control tadpole production limiting the number of adult frogs your pond produces.
Again, the size of your pond matters when stocking fish. For most small koi ponds and watergardens - 1-3 sunfish will do nicely to control tadpoles.
Absolutely. Frogs play a vital role in the pond’s ecosystem. Here’s why:
Pest Control: Frogs eat insects, including pests that annoy humans or harm plants.
Biodiversity: A pond with frogs is likely a healthy, thriving ecosystem.
Essential Ecosystem Nutrient Concentrator: Every morsel of phosphorus and nitrogen that gets moved up the food chain is nutrients that are not available to grow nuisance algae. If the frog that snacks at your pond decides to move down the road, or get eaten by heron, those nutrients may never return to the pond – this makes your pond leaner and more efficient. Great cycling of nutrients is essential for pond balance and good, clean water
Education & Enjoyment: Kids and nature-lovers enjoy spotting tadpoles and frogs in the wild.
But keep in mind:
Frogs reproduce quickly, and too many may overhunt you smallest fish and/or insects. So if your pond is brand new, you will likely have a (temporary) over abundance of bouncy friends.
Large bullfrogs may disrupt the pond's balance.
Regular monitoring helps keep the population under control. If you find you have too many frogs, I suggest introducing a predator to thin their numbers. Largemouth Bass LOVE frogs, but they also love small fish of just about any species, so choose carefully when selecting your fishy friends.
Most panfish eat tadpoles, so if you want to hinder your frog population and your koi reproduction is important to you, I suggest stocking an appropriate amount of bluegill (or other sunfish sp.) into your pond.
So, what do frogs eat in a pond? A mix of bugs, worms, small fish, and aquatic critters. While they help keep pests in check, larger frogs, especially bullfrogs, may eat more than you’d like, including goldfish or koi.
Want to keep both frogs and fish in harmony? Build a balanced pond with hiding spots, plant cover, and no overcrowding. Creating (and maintaining) a healthy pond ecosystem is the best/cheapest/most sustainable strategy for any pond. Balanced ponds cost less to manage and stay clean longer. Do your level best to have a diverse, happy aquatic domicile for your family to enjoy. If you have questions, please reach out any time to our experts at: Sales@midwestponds.com.
Frogs are a sign of a healthy pond. With the right setup, they’ll be welcome guests, not fish thieves.
