Do big/large Koi eat small Koi (Koi fry) or other smaller fishes

The question of whether big/large Koi eat small Koi (Koi fry) or other smaller fish is a common one in the world of fish keeping. The straight simple answer is- yes, they may eat your koi fry, eggs, or other smaller fishes, which are ½-1 inches or less, in some instances.

However, you could prevent this from happening by taking some simple actions.

Well, in this article we’re going to discuss those points and many more like-

Are big Koi eating small Koi? Do Big Koi eat Smaller Fishes? Why do Koi eat fry or eggs? How can you prevent them from eating other smaller fishes? What do large Koi eat? Can you put small Koi with large Koi? Will Koi eat Tetras?  And, Do Koi eat guppies? Etc.

So. Without further ado, let’s get started.

Do Big/Large Koi Eat Small Koi (Koi Fry)

Koi primarily feed on algae and vegetation. If there are enough food and space for them, they won’t bother to bite on the little ones.

But as you know, Koi are opportunistic omnivorous fish; they will eat koi fry and eggs if available to them. Normally a koi never go for a small koi or any other small fishes which are 1 inch or more. They also eat other fish’s eggs and fry if they are easy to gulp.

So, why does a Koi eat Koi fry or eggs? Are Koi a cannibal fish? or Koi a cannibal fish?
Image Souce: Canva

So, why does a Koi eat Koi fry or eggs? Are Koi a cannibal fish?

First of all, Koi aren’t cannibal fish. Consuming eggs and fry is typical for many fishes. And the reason for that is that they don’t recognize the fry as one of their own at that stage. It doesn’t matter how big the larger one is or their mouth size.  

Also, there’re other fishes who eat their own fry, such as guppies.

Now, how can you prevent Koi from eating their own fry and other smaller fishes?

It’s important to know that even though large and giant Koi may look like they are eating their tank mates, it’s not likely for them to do so (except during the mating season).

The best way to prevent them from eating their own fry or other fish’s fry, you should separate them during that time and bring them back after the fry are a little bigger.

how can you prevent Koi from eating their own fry and other smaller fishes
Image Source: Canva

However, if you aren’t able to separate them into different places, you should provide enough food and substantial space for them.  

Another thing you can do if you’re worried about your little guys being eaten is getting some live plants into your aquarium! These will give the larger fish something to snack on while also providing shelter for any little ones who might be hiding out from the larger ones.

Therefore, what do large Koi eat?

As we’ve discussed before, Koi are mainly omnivorous and are opportunistic feeders. They’ll eat almost everything they can fit in their mouth and are able to digest. However, Koi primarily feed on vegetation, algae, small insects/bugs, plants, and the fish foods you can find in a pet store.

what do large Koi eat?
Image Source: Canva

There is a full article where we’ve discussed about feeding Koi Fish.

Well, Can you put small Koi with large Koi?

From our previous discussion, you should already know the answer to this question. If your small Koi are fry or less than 1 inch in length, you better keep them in separate places. Despite that, if you want to put them together, you will need a bigger tank/pond with enough space and food access. So the bigger koi don’t bother smaller ones.

Okay. But will Koi eat Tetras?

An adult koi can reach up to 12-36 inches with proper food and care.Here’s an article on Koi’s growth. So, that’s a big enough fish to gulp a small Tetra. But as we’ve mentioned before, Koi usually don’t bother with the fish as big as 1 inch or more, or if they have access to enough food and space.

will Koi eat Tetras?
Image Source: Canva

Therefore, you don’t need to worry if your conditions are similar. Otherwise, you better keep them apart.

Then, Do Koi eat guppies?

Guppies can get as big as 2-3 inches. Making it one of the smallest popular freshwater fish and an easy target for a large koi to put its mouth on. So, during the early stage of a guppy, don’t put them together with large Koi.

Frequently Asked Questions (F. A. Qs)

Will Koi kill Goldfish?

Not really; Koi won’t kill the Goldfish. With proper food and space, Koi won’t bother the other fish.

Will Koi kill Goldfish?
Image Source: Canva

If you found your Goldfish dead, it may be from the ammonia spike or any other reason. Koi and Goldfish are peaceful fish and can live in the same tank or pond if the space isn’t an issue. And they usually don’t fight each other either.

But, in a crowded place, they could become more hostile to each other like most other fishes.

But chcek the video below. You can see the Koi is trying to eat goldfish.

And this is because the tank is totally empty, no food or plants to snack on. And the tank is too small for that size of Koi.

Do Koi kill other Koi?

In a normal condition, Koi killing other Koi wouldn’t be the case. Yeah, the larger Koi could eat the fry or eggs. But, killing other Koi isn’t usual, as they aren’t territorial or aggressive in nature.

Do Koi kill other Koi?
Image Source: Canva

However, in certain cases like- poor diet, water condition, unsuitable mates, and similar problems can make them bully other fish.  

Can Koi grow big in a small pond?

Koi are hardy fish and can survive some difficult conditions without a sweat. And they can grow bigger in a small pond too. But a bigger pond is necessary to bring out the full potentials of your Koi.

Can Koi grow big in a small pond
Image Source: Canva

Although every expert will recommend a bigger pond for Koi, pond size isn’t the only thing that happens to be affecting your Koi’s growth. Food, nutrition, genetics, and many other factors play vital roles in a koi’s growth.


Though I didn’t mention it in the main article, the answer is debatable whether big Koi eat small Koi or other small fishes. Some argue they never saw a koi touch other smaller Koi, and others say the large Koi eat smaller ones.

But one thing most people agree, Koi do eat fry and eggs.

In this article, we discussed every information we know and found regarding this matter. Even though you aren’t satisfied with what you’ve learned so far, feel free to leave your opinion and query in the comment section. And let’s discuss the matter further and learn more.

So, until the next time, stay safe and healthy, and happy fish keeping!!!


  1. I have 16 inch koi orange and white has eaten three of my 10-12 inch one white and two yellow. Very 😢

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