How Often Does Koi Fish Lay Eggs? All Fish Breeders Should Know

Koi fish are gorgeous ornamental species in any environment. At the right times, these fish will begin to reproduce in your tank when they are mature enough.

However, how often does Koi fish lay eggs? Every year, female ones usually produce spawn in late April for 6 – 7 years.

Their breeding process is quite simple, but you will need to intervene at a few critical stages. Therefore, you can encourage them to spawn.

If you are curious about the reproductive cycle of this fish species and some tips to care for newborns, it’s time to click on this article.

Let’s scroll down to discover more!

How Often Does Koi Fish Lay Eggs?

After these fish reach their sexual maturity, Koi fish usually mate once yearly for roughly 6 – 7 years.

Many breeders want to get these fish to mate to reproduce twice a year. Yet, the female ones will lay considerably fewer offspring in the second breeding.

These marine creatures reproduce in ponds as long as the temperature of the water is between 65 and 70 degrees Fahrenheit. Late months in spring are the most common times for their breeding to occur.

While these are the breeding months of this species, their actual spawning period lasts around two or three days.

Whether in ponds or aquariums, egg-laying and its procedure put on a similar production.

When a male sees a female be about to produce eggs, he tries to pursue her. This act will encourage her to lay spawns; he can be the first one to fertilize her.

When the female koi fills up with its eggs, she resembles a marble bag. It means she’s ready to release her spawns on pondweeds, breeding mats, or laying ropes.

If you would like to encourage these fish to breed in a tank, you’ll have to replicate the perfect spawning water conditions. Ensure that the female fish have sufficient plants where they deposit their spawns.

Koi reproductive frequency

Reproduction & Breeding Of The Koi Fish

If you want to increase the Koi newborn population, it’s best to learn about the production process and breeding. These fundamentals are also helpful to remember if you care for fry from the fully adult fish.

Sexual Maturity

Although these creatures are sexually mature as they reach the age of two, breeding them is not advisable.

Once most koi types achieve sexual maturity, they should be approximately three to four years old.

That’s when female fish begin to deposit the most eggs. The ones that result have a greater chance of surviving to adulthood.

Number Of Eggs

Professional breeders generally figure out how many spawns a female fish can produce by keeping track of her weight.

A sexually mature fish measuring about 1 pound can deposit up to about 50,000 spawns during a reproductive season.

That figure may appear ludicrous. Nevertheless, only around 60 percent of the total will survive over the hatching stage.

Breeding Stages

The breeding process often includes three stages, as shown below:


Male koi participate in a short-lived mating practice one day before females release the spawns.

The male often pursues the female and will very deliberately touch her to encourage her to go to the water’s more heavily planted regions.


When a female fish is ready, she will willingly swim to the pond’s shallow margins and lay her eggs.

She will release eggs anywhere she sees more greenery in a tank. Those spawns will stick to the surface she comes across.

You can loosely tighten an egg-laying rope in that tank so that the female will lay spawns on it, and you can remove the eggs quickly.

You may prepare ahead of time by adding hornwort to the tank if you like to maintain the reproduction as natural as possible.

Laying Eggs

Fertilization occurs swiftly since the male is nearby during reproduction. The male Koi can begin releasing sperm on large numbers of spawns after the female releases the eggs.

Reproduction and breeding

Tips To Encourage Koi Spawning

Although the female releases a large number of spawns, not all of them can survive after hatching. So, you may need some tips to encourage their spawning.

Make Areas For Spawning

Many plants with leaves and submerged roots can benefit your fish.

These will provide a safe environment for the eggs to hatch, while the plants provide nutrition and shelter.

Clean The Tank Or Pond

Change 10 percent water monthly and purchase test kits to keep pH, nitrate, ammonia, and other factors in check during the year.

Protect The Eggs

Your Koi newborns may die mainly because of more giant predators and poor water surroundings.

It’s best to use a filter to remove toxic chemicals in water like extra nitrates and ammonia, which increases the longevity of spawns.

Koi fry

What Do Koi Fish Eggs Look Like?

The Koi eggs are tiny bead-like specks that grow to reach a diameter of some millimeters.

They should have a dark tone without white specks and be practically transparent.

These spawns will stay relatively tiny in some first hours following a successful reproductive event.

After 24 to 48 hours, you can easily distinguish unfertilized eggs from fertilized ones due to the fuzzy milky white color.

Do you need to know more about two types of Koi spawns? You can watch this video:

The eggs

How To Care For The Newborn Koi & Ensure That They Grow Normally?

If it’s your first time raising these marine creatures, here are some helpful tips for caring for newborn fry to help them thrive.


The fry will only eat their own spawns three days following hatching, receiving all of the nutrition they require from that one supply without being fed.

The best time to feed them is after the fry can freely swim. After four weeks, you can let them eat solid food four times a day, such as freeze-dried krill, freeze-dried shrimp, or crushed chicken eggs.

Living Environment

The fry will often be weak in the first few weeks of their life. They are vulnerable to factors like water temperature change or parasites.

It’s best to notice the water quality, volume, and temperature. For instance, you should use the filter to remove toxins and maintain the temperature between 70 and 75°F and the pH level from 7.2 to 8.0.

The fry

Wrapping Up

This article has eventually got to the bottom of your question: “How often does koi fish lay eggs?”

Koi fish usually mate once a year; however, some Koi will lay eggs twice per year. Female Koi usually lay eggs in the spring.

Hopefully, this post will be helpful for you. If you have further questions, leave a comment below. Thank you for reading!