If you find yourself Googling, “how long for koi eggs to hatch”, chances are you have a lovely little clutch of eggs and are excitedly awaiting their hatching and arrival into this world. Congratulations!
Raising koi fry is a very rewarding activity and you are in for a real treat in watching your new baby koi fish grow.
Let’s take a look at the lifecycle and breeding habits of a koi fish and help you figure out how long it takes those eggs to hatch and what you can expect once they do!
So, How Long?
In general, it takes around four days for a koi egg to hatch.
Depending on your water temperature and quality, though, it can take up to a week.
It is key that if you plan on breeding your koi fish, you remove the breeding pair from the original pond and put them into a breeding tank or pond.
This allows you to remove the adult koi once the eggs have been laid to prevent the adult koi from eating the fry.
Additionally, you can also keep a better eye on the eggs and fry once they hatch, allowing you to provide the best possible care for your new batch of baby koi.
Let’s explore the life and breeding cycle of a koi to help you understand exactly what to expect and give you a more finite timeline.
Generally, the koi breeding season lasts from February until May, though this may vary based on your local climate.
Professional breeders manage to breed for a longer window each year by curating a controlled environment within a tank or pond set up but for most hobby breeders, it is safest to stick to this natural breeding season at first to ensure you are not putting stress on your koi.
Select two koi from your pond with traits you enjoy or would like to see in other fish and place them into a separate breeding pond or tank.
Provide them with lots of plants or a fry net to help keep the eggs stable once they are laid.
Keep in mind that these koi’s babies may not actually resemble the parents; if you do not have the lineage information on your fish or they are a basic pet store variety, you may actually end up with hundreds of different traits within your clutch of eggs since they are typically not bred in conditions that are as closely controlled and monitored as traditional Japanese style breeders.
When selecting your koi, it is very important to make sure they are mature and healthy, above all else.
Fish that are sick can be killed or hurt during the breeding process and may not even produce viable eggs.
You want healthy fish with males being older than three years and females being older than three but less than six to eight.
This is when their fertility and viability of young is the highest.
When koi fish breed, they can be rather violent.
You can expect the male koi to nip and take part in head butting and pushing.
The males do this to try and force the females to lay their eggs on the netting or plants you provide.
If a koi becomes injured or appears to be too stressed, remove it from the pond and try again with other koi.
They simply may not be compatible.
However, if they are compatible, you will soon see eggs in your pond.
Remove the male immediately following the breeding, which happens in several sessions.
The female can also be removed and placed into a nursery tank to recover from breeding.
Now, your eggs are ready to mature and hatch!
Koi Egg Care
Once you have eggs, add an airstone to the pond or tank to provide oxygen to your developing koi.
Leave them be, for the most part, aside from ensuring their temperature is regulated and they have enough space.
After around four days, you will notice them beginning to hatch.
After a week, most of the koi should be hatched.
Give it a few more days after the majority has been born and remove any dud eggs; these are likely not viable.
From there, you can follow koi fry care and provide them with the stepping stones to mature into lively, gorgeous new koi fish!
What to do If You Find Eggs in Your Pond
Sometimes, your fish will decide to breed on their own.
This is normal and what they do in the wild but if you want to ensure your babies survive, it might be a good idea to remove the eggs from the pond and place them in a breeding tank with fry ropes or other tools for the babies to use in growing.
Leaving the eggs in the pond will almost definitely result in many of them being eaten before they ever hatch and most being consumed once born because they are small enough to be prey.
This is simply the natural reaction may adult koi have to babies in the water and cannot be helped.
Your best move is removing them to give them a chance to mature and become a large enough size to not appear as food to your mature, larger koi.
If you do leave your eggs in the pond or do not notice them until they have hatched, try catching the fry and moving them.
This will give them a chance to mature and, if done gently and carefully, will not harm your fish.
Move them to a pre-cycled and acclimated pond or tank with the same parameters as their usual pond and provide them with something to hold onto until they are strong enough to swim.
Be very gentle and patient and they will likely be just fine, though you can expect to lose some since they are very fragile.
Raising baby koi is a very fun and interesting way to add more to your population and provides you with the ability to customize and curate your koi pond and breed for exactly the qualities you are interested in if your koi’s lineage allows for it.