A common question that we hear from fish keepers is, “How many eggs do koi lay?” To provide a detailed and accurate answer to this question, we must first fully understand the reproductive process of koi.
The male and female begin the reproduction process by swimming parallel to each other in an upright position with their vents close together.
This movement stimulates both fish to release sex hormones into the water.
The female releases her eggs as the male releases his sperm (aka “milt”).
The milt adheres itself to the female’s body as well as her fins and tail.
Eventually, both fish will roll over on their sides and move forward in an attempt to fertilize all of their off spring before they die or are eaten by predators.
Milt, although found in both male and female koi, is produced and stored inside the testes of the male. The testes are located behind and underneath his intestine. When fish breeders artificially strip or extract milt from a koi, it can be collected in a small container.
It will appear clear to slightly yellowish in color depending on the age of the fish from which it was taken-older males tend to have more yellowish milt than younger males.
The quantity of milt collected depends on the size of the fish from which it was extracted.
For example, if you were to extract milt from a large male that weighs ten pounds or more, you will end up with a significant amount of milt. If you were to collect milt from smaller males, it would be less.
Milt is also affected by the time of the season in which it was collected.
During the summer months, when water temperatures are high, koi will produce more milt than during the winter months when water temperatures drop and koi become sexually inactive.
Because female koi release their eggs into the water as they are being fertilized by male fish, there isn’t a distinction between what one should consider “milt” or “eggs”.
They are all considered offspring until they hatch. Now that your knowledge of reproduction has increased tenfold (or maybe just five).
How many eggs do koi lay?
A female koi will generally lay between 300 and 800 eggs per spawn. On average, a large 10 lb female will usually produce about 600 eggs per spawn. Of course you can always find an exception to the rules when it comes to nature . . . but keep in mind that exceptions are not common.
how long does it take for koi eggs to hatch?
It really depends on the water temperature that the eggs are kept in. If you are trying to hatch koi eggs, I would recommend the following temperature chart be used as a guideline for how long it will take for your eggs to hatch.
Temperature Degrees Fahrenheit: Time:
- 50: 1-3 days
- 60: 3-5 days
- 70: 5-7 days
80: 7-10 days/2 weeks or more (It is not recommended to keep koi eggs at this temperature for the entire time it takes them to hatch) *Please note that these times are estimates and can vary based on several factors such as water quality and species of koi. If you are looking for a more accurate time to hatch your koi eggs.
When Do Koi Spawn?
Koi usually spawn in the spring when water temps get up to 65 degrees. Koi like all of us, don’t like the cold and will not reproduce until the weather warms up. The male koi can begin breeding at age 4 or 5; for females, it is less clear cut.
Females can begin to breed as young as two, but if food is plentiful and the fish has access to proper nutrition, they may not start breeding until age 5 or 6. The female can store sperm, so she will produce a few spawnings every season even if there isn’t a male present.
How long do koi live?
The average life span of a koi fish is 30 years. Some koi have been known to live longer than that, but I wouldn’t expect anything over 45 years or so. Koi get big – 20 inches and up. And they just don’t seem to last as long as other types of pond fish such as goldfish which can get up 15 inches and live to be 20 years old.
Koi will continue to grow throughout their life, however slowing down as they age. So a 10 inch koi would be considered very young compared to an 18 inch koi. One rule of thumb is that for every 1 inch of koi, you can figure it’s about 8 years old (just a rough estimate – it doesn’t work for every situation).
How long after breeding does it take for koi eggs to hatch?
The answer is actually quite complicated. The fertilized eggs of the common carp, including the koi, usually require from 16 to 28 days for complete embryonic development . Some have been reported to take as little as 12 days, and others as long as 40.
Most koi take about 21 to 28 days though. The speed at which they develop is dependent upon water temperature (the cooler the water, the longer development time), oxygen content (the higher the oxygen content in the water, the faster they will develop) and food supply.
This last one is probably the most important. The more food they have, the faster they will mature – up to a point.
After getting big enough where food isn’t really limiting anymore, koi growth slows down considerably.
After hatching, it can take another month or two before they are ready for sale because of their size and the time it takes for them to fill out.
So counting the time it takes for the eggs to hatch, they are actually 4 to 5 months old when you buy them (assuming you buy your koi in the spring – if not, add on another month or two).
What is this red string?
It looks like some sort of lifeline. There is a real scientific explanation for this: It’s called a mycobacterium and is known to cause disease in fish. On the outside, it looks like string, but on the inside when you look really close you can see that there are all sorts of things moving inside – kind of like an underwater collage.
What is that white thing in the koi pond?
It’s not a fungus, it’s actually a type of parasite that feeds on dead skin cells and other debris. It looks like little clouds because they are so fast-moving. They eat so much dead skin that sometimes you can’t even see the fish underneath them! This is known as “ich” or Ichthyophthirius multifiliis.
Koi are tough, though, and they can handle it if you don’t use too much chemical medication to get rid of this stuff. The mycobacterium is also very common in koi ponds but doesn’t seem to affect them at all.
What do koi eat?
All fish are opportunistic when it comes to feeding. They will eat whatever they can get in their mouths when they see it, but some foods are better for them than others. Koi are omnivorous, which means they eat both plants and animals.
In the wild they would normally feed on insects that fall into the water where they live, or whatever plants are growing in the pond. A portion of good quality food will have a lot more animal ingredients than plant ingredients, but I’ve seen them eat lettuce!
Do koi eat goldfish?
Koi are not likely to try and eat goldfish because they don’t look like anything koi would normally go after. Goldfish actually grow much bigger than the koi in the same size pond, so typically they will leave each other alone.
But if you have them in a very small tank, or if your goldfish are sick and losing weight all of sudden, then there is a chance that the koi may eat them.
What do koi sound like?
It’s actually kind of hard to tell what they sound like. When you’re in the house it’s not very loud (unless you have an indoor pond, then it’s pretty loud). But when you get near the koi pond, sometimes you can hear them “talking” if there are enough of them.
What do goldfish sound like?
It’s actually hard to tell what goldfish sound like too. They do make some sort of sounds when they are in trouble, stressing out or dying – kind of like a dog whistle. You’ll know it when you hear it!
Do koi eat frogs?
It’s not likely that your koi would go after frogs because they will most likely eat any plants first. But again, koi are opportunistic feeders so if there are no other choices then yes!
What kind of fish do frogs eat?
Frogs mostly just stay underwater during the day and go back to land at night. They will sometimes hang out near water but won’t really drink it. They only eat very small insects, so they probably won’t go after your koi.