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What Can Koi Fish Eat? 35+ Foods Koi Can (& Can’t) Eat

Disclaimer: This is by no means an exhaustive list. Koi can eat a wide variety of foods. It's a good idea to learn what types of foods your koi will eat, you may be pleasantly surprised.

Koi are often regarded a little like the dogs of the sea; they’ll kind of eat whatever you’re eating because it’s delicious and call it a day. While some human food is perfectly acceptable for koi, some things will flatline your fish faster than you can say “whoops”. One of the best things about owning koi is seeing them come at you, looking for something to nibble on - and surprising them with something tasty AND nutritious.

So what can you feed your koi beyond koi pellets and store-bought “nutritional kibble”. We'll dive into the details on what koi can and cannot eat below.

Table of Contents

Do Koi Eat Other Fish?

This is one of the most common question we see in the fish world. Since Koi can easily jump two feets, and some varieties can get to even three feet, it’s normal to think that big equals mean. However, this is not the case with koi fish.

Do koi eat goldfish? 

Both Koi and Goldfish are a docile, calm fish species often seen living together in ponds. Most goldfish species stay smaller than even the smallest of koi and only grow to about 12 inches, so you’ll be able to tell the difference between them easily. Even if a goldfish becomes sick or injured, koi will not attack or eat your goldfish.

However, it should be noted that goldfish under an inch in size may  be mistaken as food by larger koi, so make sure your goldfish is at least a few inches long before introducing them to your pond.

Do koi eat their young, or small koi in the same pond? 

Koi are omnivores and can eat a variety of plants, insects, fish eggs, and algae. Sometimes they will also eat fish spawn and eggs, including their own eggs. This is not because koi are a combative fish - they are incredible docile - but because koi have a large appetite and enjoy eating on and off all day. As long as the koi recognizes the fish as a fish, it will leave the fish alone. This means that koi can live with any other docile fish, not just goldfish.

Do koi eat spawn or their own eggs?

Koi love to eat, which means that they are not always particularly picky about what they eat. While koi will absolutely not attack another fish if they recognize it is a fish, they will eat fry, eggs, and fish spawn that happens to be in their pond, especially during the summer months when koi metabolism is the fastest. A fish has got to eat!

Do koi eat other fish that are not koi? Do koi eat smaller fish?

Koi do not eat smaller fish and are happy to live with as many fish as they can. Even if a tank is overcrowded or the koi are underfed, they are not known to attack each other. They will also not attack goldfish or other fish, such as plecostomus and other feeder fish. Koi do not view other fish as enemies and will strive to avoid conflict with any and all other fish.

Can koi eat shrimp or prawns?

Koi are omnivorous, meaning they’ll pretty much eat anything, they can eat shrimp and prawns. In fact, they love shrimp! Shrimp are full of yummy nutrients that make them a great treat for your koi. For smaller koi, make sure you either get smaller salad shrimp or cut larger shrimp up into pieces for easy consumption. Large koi can consume shrimp whole. Raw or cooked is fine - heads or no heads is also fine - koi are not picky when it comes to tasty and delicious shrimp.

However, koi will overfeed themselves on such delicious morsels such as shrimp, so ensure you feed them shrimp only during the summer months and in moderation.

Can koi eat minnows or guppies?

Small fish like minnows and guppies often accompany koi in ponds because while the koi can grow up to three feet, guppies stay small and will continue to eat mosquito larvae and other unwanted pests in your pond. Often, koi and guppies coexist nicely. If the koi are fed well and often, many koi will even spit small fish like guppies out if they mistakenly inhale them. Koi are not predatory fish, especially as they get larger.

However, during fast metabolism months when the pond water is warm, it is easy to underfeed koi. While your koi won’t starve if you forget to feed them, they can start to eat whatever is in your pond. Snails, algae, pond plants, and yes...guppies. A hungry omnivore isn’t picky!

Doi Koi Eat Bugs, Meat, Tadpoles, Frog spawn

In this section we'll discuss whether Koi can eat bugs, insects etc

Do koi eat larvae or maggots?

Because koi are omnivores by nature and often feed off a plethora of different things in the wild, they can easily consume things like larvae and maggots. Maggots are a great source of protein for koi and many of them will find them delicious and eat them quickly.

However, some maggots that are used for fishing are dyed using synthetic dyes. These maggots are not good for koi and should never be fed to them under any circumstance. Plain maggots make for a good treat.

What insects can koi eat? Do koi eat live bugs, like earthworms, leeches, pond snails or slugs? 

Koi love bugs. In general, if a bug would naturally wonder into or land in a koi pond, it’s probably fine for the koi to eat. Occasional bugs are great for koi, but you should never feed them commercially produced bugs that could contain harmful pesticides or colorings. If you keep compost, pulling some worms out from the compost to feed to your koi is a healthy and fun idea, and your koi will enjoy their meal immensely. Only feed koi organic bugs and insects (or bugs you find in the wild).

As far as snails go, koi will never pass up a snail. Some of their favorite snails to eat are ramshorn snails and trapdoor snails. If a koi can get to the snail, it will eat the snail - period! Ramshorn snails and trapdoor snails are non-aggressive and peaceable, so the chances of them living together with koi without becoming dinner are slim to none. Simply put, don’t put snails in your pond if you want them to live with koi!

Do koi eat dried mealworms? Can they eat other dried bugs, like crickets?

Koi loved dried bugs as well, and mealworms and crickets make for a great occasional snack. However, the same rules apply as they do to the other bugs: make sure you’re only buying organic insects or feeding them ones you’ve caught in the wild to avoid pesticides and dyes that could harm for your fish.

In addition, dried insects should not be the bulk of your koi’s diet. Koi are used to consuming food that is 80% water, and dried worms and crickets don’t have time to absorb enough water before they are eaten, so make sure you limit them carefully and have an excellent protein skimmer installed.

Do koi eat tadpoles, frogs or frog spawn?  What about polliwogs, toad tadpoles or newts? 

The answer to this is mostly a resounding yes. Koi love frogspawn and tadpoles and will eat them the second they see a wiggle out of the corner of their eye.This includes newts and newt spawn. However, in some areas newts are protected by strict laws, so if you happen to spot a newt near your pond, it might be best to relocate it before it gets eaten.

Polliwogs, toad tadpoles, any sort of frog or newt egg are all up for grabs and will not harm your fish. However, if for some reason you find it necessary to treat your pond and have to add a chemical to it, it will likely kill any tadpoles in the pond. Koi will likely not eat the dead tadpoles, so make sure you remove them so they do not rot and lower the quality of your water.

The problem comes when we start to talk about toads. While koi will try to eat toads, they often spit them out because both toads and toad tadpoles have a bitter taste. Toad eggs, in small quantities, are okay, but if you see excessive amounts of eggs, it is best to remove them. Toad tadpoles and toads in general are edible, most fish avoid them and they live harmoniously, more or less, with koi.

The one exception is bullfrogs. Bullfrogs are very aggressive and will eat just about anything, including small koi fish. Anything under a foot could possibly be a meal to a bullfrog. If you happen to see one, relocate it, especially if your fish are small.

Will koi eat ducks or geese?

Koi will not eat any sort of aquatic fowl that takes a flying break on your pond. Even babies are safe, even around the biggest of koi. Koi are completely passive and will not become aggressive with other animals and, in fact, enjoy the company of people, other fish, and even ducks and geese.

If wild ducks land in your pond, it’s best to either put a net around your pond or take precautions to disallow the ducks from landing. This is because wild ducks can carry parasites that can harm the water quality of your pond or your fish themselves. Ducks also produce water soluble poop that will send your filters into overtime and lower the water quality significantly. While ducks and koi get along swimmingly, it is still best to discourage them from your koi pond. Build a duck pond instead.

Do koi eat turtles or snakes?

No and no. In fact, the biggest problem with putting turtles in a koi pond is that the turtles can damage or even eat the koi. There are accounts of the two cohabitating happily as long as both are fed, you have an excellent large debris filter, and your koi are on the larger side. However, caution must be exercised - and not because the koi will bug a turtle at all. If you do decide to try and put a turtle in your pond, only introduce one. One turtle’s waste and presence is more than enough for even a large koi pond.

There have been a few accounts of a koi consuming smaller snakes - remember, koi are omnivores - but for the most part, it will only be your fish that are in danger if a larger snake happens to come by.

Do koi eat string algae? 

Yes - koi will absolutely eat algae, including string algae. String algae is actually a great source of nutrients for koi and grows naturally in ponds. However, string algae can easily take over an entire pond  and make it impossible to see your fish, so many koi pond owners add a high-quality protein skimmer to rid the water of nutrients for algae.

In addition, koi eat moss and other types of algae from the side of a pond as well. They love it!

Which Plants Can Koi Eat?

Are aquatic plants like water lilies, lily pads, duckweed, anacharis, watercress, frogbit suitable for koi to eat. 

As you already know koi are not picky eaters and don’t have a problem eating vegetables. If they can get to a plant, whether it’s a water lily or an iris or anacharis, they will eat it. And they will eat it down to the roots and, in some cases kill off the plant entirely. Koi and aquatic plants do not go well together, unless you just want your plants to be an appetizer.

Do koi eat human vegetable plants, like lettuce, kale, broccoli or spinach?

Koi love greens, especially ones they wouldn’t get in the wild! Since the moisture content is so high in lettuce and spinach, they are two koi favorites. Broccoli and kale should be parboiled for 3 - 5 minutes before they are fed to koi, but once they are, there is no doubt that your koi are going to eat them quickly and efficiently.

Can koi eat leaves, grass, and other vegetation that might be in or around my pond?

While koi will try a bite of almost anything, generally they will not eat grass, leaves, and other plants around the edge of your pond. One reason is because they can’t really get to them, and if they are well-fed, they have no reason to try. If leaves fall into your pond, a fish or two might try them out, but most won’t eat them as they hold little to no flavor and nutritional value for your koi. Domesticated, ornamental koi don’t usually eat grass either, but a type of carp called the grass carp will literally beach itself on the side of a pond trying to get to the foliage near the edge!

What Plants Do Koi Not Eat?

A better question to ask here is, “how can I prevent my koi from eating all of the plants around and in my pond?” Unfortunately, koi love just about any plant you throw at them. They’ll strip duckweed out of your pond too, especially if you have more than just a few koi.

That being said, there are ways to include plants in your koi pond. When building your koi pond, ensure you section off some areas with rocks or by building a shelf so that a plant can rest there and your koi can not easily get to its roots. Koi will not jump to get to a plant, especially if they are well-fed otherwise. Make sure your koi get tons of greens, such as broccoli, lettuce, and peas. This will ensure they are well fed and away from the plants in the pond, as it will sink and be available for bottom feeding later in the day when the fish are hungry again. However, there is no guarantee a tasty aquatic watercress won’t get a nibble before breakfast unless it is safely allotted space away from your fish.

What Human Food Do Koi Eat?

Can koi eat carbohydrates, like bread crumbs, rice, popcorn, potatoes, or pasta? Do koi eat Cheerios or other cereal, like Rice Krispies and Kix?

The general rule here is that if you can eat it, technically your koi can eat it. However, white flour and quickly processed carbohydrates like potatoes, white pasta, and white rice can be harmful to your koi, especially as a staple or regular treat. If you are going to feed your koi carbohydrates, make sure they are whole wheat. The only exception is, believe it or not, Cheerios. For some reason, koi absolutely adore Cheerios in its simplest form (so no honey nut flavor, for example). Cheerios should be soaked for 2 - 3 minutes before you throw them to your koi, but they absolutely love Cheerios.

In addition, you should only feed your koi COOKED potatoes, rice, and pasta that are whole grain (not made with any white flour at all). This is because these items can swell and cause obstructions in your fish, killing them within hours.

Heavy carb diets can also lead to obese fish that suffer from health issues, so ensure you only feed these items - including Cheerios - as an occasional treat.

Do koi eat vegetables, tomatoes, corn, peas or raisins? 

Koi should not be fed any vegetable with a hard outer casing because the casing is hard for them to process. Vegetables like peas can have the casing removed, but corn is a bit harder.

However, corn and cased peas can be dried and ground up into a semi-fine dust that your koi will absolutely love. Most other vegetables, like tomatoes, can just be parboiled after they have been coarsely cut.

Do koi eat garlic? CAN koi eat garlic?

Most koi love garlic. In fact, garlic is not only good for your fish, but they also love the smell. It attracts them in the water. So if you’re introducing a new food to your fish, coat it in either garlic or the dust of their regular pellet food to convince them it’s tasty enough to try out.

Do koi eat healthy human foods, like nuts and oatmeal?

While nuts are not recommended for koi because they are hard to digest and can cause major obstructions in their bowels, oatmeal is not recommended because it can swell and cause obstructions, even though it is a healthy grain and nutritionally would be fine for your fish.

Can Koi Eat Regular Fish Food?

Can koi eat food meant for other fish e.g catfish food, sturgeon pellets, cichlid food, betta food or goldfish food?

There are particular foods that can be fed to other pond fish that should not be used as Koi food. These include bird seed, corn, peanuts, bread, rice and peas. These items are also often included in other pond fish foods and bird foods. Seeds, corn and peanuts are poor Koi food as well because they can also cause blockages because Koi can’t digest them.

Your koi’s regular diet should be of the koi pellet variety to ensure a balanced diet. The exception is perhaps goldfish food as goldfish are closely related to koi and both can often eat the same food mixtures. Simply read the label to ensure you are getting a food that is compatible for both.

Can koi eat flake food?

Smaller koi can eat flake food that is specially formulated for koi. In fact, it’s difficult to make pellets small enough for baby koi, so flake food is best! However, once the fish are big enough for a pellet and other healthy foods, they no longer need the flake and it should be discontinued.

Can koi eat turtle food?

While there is lots of crossover between the nutritional needs of turtles and that of koi, it is not recommended that you feed koi turtle food. While some will absolutely not bother them, because it is not balanced for koi, koi pellets should also be offered to ensure nutritional needs are met.

Can koi eat dog food?

While dog food is a perfectly acceptable treat for koi, and it won’t do them any harm if some gets into their pond, it should not be a staple of the koi diet. Think of it this way: for the first 30 years of your adult life, you probably won’t notice the effects of eating a high-fat, low-nutrition diet.

Eventually you will, and it may even shorten your life. So while younger fish may not show effects of malnutrition from a dog food diet (since dog food does have some of what koi fish need), they will likely develop health issues or die prematurely.

Do Koi Eat Their Own Poop?

No. In fact, it is a long-running myth that fish eat their own poop because they can. Most fish will inhale some of their own feces on accident, and then readily spit it out once they realize it doesn’t taste very good. Fish may also pick missed nutrition out of their poop and avoid the parts they already digested.

Koi are bottom feeders, so they do have a tendency to graze, and might run into some of their own droppings. However, a good filter should minimize this contact, as the fish gain little to no nutritional value from this and don’t enjoy it.

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