A Guide to Raising Koi Fry

Raising Baby Koi

A Guide to Raising Koi Fry

So, if you are reading this, chances are you have successfully bred your koi and have some fry ready to go or are planning to breed them sometime soon. Either way, you have come to the right place! Let’s look at how to go about raising koi fry!

Raising Baby Koi
The First Days for Koi Fry

Raising koi fry does not have to be a scary experience. What sounds terrifying and delicate at first glance is actually a relatively easy project to undertake if you are prepared and understand the lifecycle of a koi fish.

Within the first few days of hatching, your koi will be at their absolute most vulnerable. It is recommended you purchase an item known as a “spawn mop” or “spawn brush” to give the newborn koi fry a place to hold onto until they can begin to move about on their own. These can be picked up at most fish product retailers or through Amazon.

Some of our favorites include:

This product is a large piece of faux grass that works to mimic the natural appearance of a koi fish’s breeding ground. The grass can either float at the water’s surface or be weighed down to allow a lower holding zone for the fry. This is a safe area for the babies to hide and can be washed and reused many times over thanks to its durable, reinforced nature!
A bit of a different take than the Penn Plax product, this is a rope-like faux plant that allows the koi fry to drift in the water on thick tendrils. The brand claims it to be fish safe, reusable, and very durable, as well.

You should ideally have this already in your fry’s holding tank while they are still eggs so that when they are born they can readily attach to the nets. The average wait for koi eggs to hatch is around four days after being laid, though the breeding process can take quite some time. Once you notice eggs, immediately remove the parent fish and add in the fry net of your choice.

For the first two to three days of their life, the fry will feed off of their yolk sac. You do not need to feed them during this period, as they cannot even eat yet. Very young fry actually lack mouths!

When Koi Fry Start to Swim On Their Own

Once your koi begin to move around a bit on their own, they are probably ready to eat. This usually occurs around the tenth day, but can take longer or occur sooner depending on your water temperature (more on that in a bit).

Start off with either a liquid food made of brine shrimp or daphnia or a fry powder made from crushing up regular koi food with a mortar and pestle. Do not feed more than what can be consumed within 5 minutes to prevent polluting the water.

As they grow, make the food source larger to grow their stomach size. Be sure the food is not so large that they will be injured or have digestive issues.

During this time, it is very important that you keep the water aerated. The koi are still too small for any sort of actual filter so try adding in air stones or other gentle aeration tools that will not blow them around but will provide plenty of oxygen. You also must maintain a temperature close to that of your pond and generally keep the eggs a bit warmer, even, if you want a successful hatch within the four-day window.

As they grow, make the food source larger to grow their stomach size. Be sure the food is not so large that they will be injured or have digestive issues.

Raising Baby Koi
Reducing Your Baby Koi Numbers

While you may get attached to all of your cute new baby koi, it is sadly not realistic to keep all of them. Once your koi are around one inch or a bit more, you probably need to cull some of the less healthy fish or those that are not interestingly patterned or otherwise “valued” (not that all koi aren’t valuable in their own right, more so keep ones that are vibrant). This means humanely dispatching or giving away koi fry that aren’t ones you wish to keep and raise.

This is a hard process but is one of the realities of raising koi. Keeping an entire batch of fry leads to overcrowding, food competition, and the entire group suffering. A second culling needs to happen when they are around four weeks old and a third once they reach two months. By the end, you should only have around a quarter of what you started with, if that.

Raising Baby Koi
Introducing Koi Babies to A New Pond

Once your koi are around four to six months old, they will likely be large enough to put them into your main pond. To do this, first place them in bags with water from their holding tank and allow them to float on the surface of the pond and acclimate to the water. Release them into the pond after an hour or so of acclimation and monitor them to ensure they are doing well.

If you release them too soon, they may become food for the other koi or be injured. Try to let them get reasonably large and close to size with your smaller adult fish to ensure they thrive in their new enclosure.

Raising Baby Koi
Raising Koi Fry is Rewarding

Raising fry is a rewarding task that can give you quite a few new fish for your pond. Though it may seem scary, with a bit of knowledge you can make the process a breeze!

Just take your time and always ensure your koi are safe and moving along nicely in their growth progression. Patience is key!

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