What Do Koi Eggs Look Like? (And Are They Fertilized?)

by Tory Jon | Last Updated: June 14, 2021

Koi eggs are an interesting topic of discussion for koi keepers.

They can be fertilized or unfertilized, and it is important to know the difference as fertilized eggs can hatch koi fry within a week! This can be shocking if you, and your fish pond, are not ready for a population boom.

In this guide to koi eggs, you'll learn what koi eggs look like, how to tell if they are fertilized, and pretty much everything else you need to know about the first stage of a koi's life.

What Do Koi Eggs Look Like in a Pond?

Koi eggs look like very small beads that can vary from clear to yellow or amber. Some compare koi eggs to tapioca pudding.

Tip

If you notice eggs in your koi pond and they are black instead of clear or amber, you likely have toad eggs.

And there will be a lot of them. A large female koi can release hundreds of thousands of eggs at a time!

You'll likely notice the koi eggs attached to pond plants and other vegetation found in the shallow waters of your koi pond. If you are actively trying to breed your koi fish, providing plenty of plants, such as hornwort or water hyacinths (some use artificial spawning mats and ropes), will provide them with the ideal habitat to lay eggs.

If you test your pond water regularly, you'll notice a spike in ammonia levels, followed by a spike in nitrites after koi eggs have been laid. You may even notice foam forming on the surface of your pond.

What Do Fertilized Koi Eggs Look Like?

Fertilized koi eggs look like small beads that are clear or very light brown with small dots on them.

Here's a video of koi fish eggs 46 hours after fertilization.

Koi eggs that were not fertilized will turn white and appear fuzzy. It's a good idea to remove these eggs from your pond to improve water quality and increase the chances of survival for your fertilized eggs.

How Often Do Koi Fish Lay Eggs?

Koi fish lay eggs once, sometimes twice, per year. The time of year koi lay eggs is typically between May and June.

But, this will really depend on the water temperature of the pond, as they prefer temps between 65 and 70 degrees to spawn.

Spawning typically occurs early in the morning, with male koi aggressively chasing and nudging females around the shallow areas of ponds.

And you may notice your koi spawning in stages, stopping to eat their own eggs as fuel, before continuing.

How Many Eggs Do They Lay?

Female adult koi will lay between 20,000 to well into the hundreds of thousands of eggs in just one spawn!

But, how many of those koi eggs survive?

Koi will eat a large portion of that number (upwards of 90%!) if you don't separate the eggs from the fish. So, to stop your koi (and predators such as birds and raccoons) from feeding on your koi eggs, you should remove them from the pond and into a safe tank or separate breeding pond for safe hatching.

And in no time, you'll have babies (see what baby koi fish look like) that will quickly grow into beautiful, colorful adult koi.

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