When your female Koi becomes old enough (3-5 years old) her body will produce eggs. When the water temperature increases to 65-70 degrees you will begin to see the signs of spawning. There will be a lot of chasing, the female will stay to herself near the bottom, and they will eat a lot of food. It is said that mating will begin when there is a full moon and the eggs are released early in the morning. It is the male's job to help her remove the eggs and then fertilize them.
In some cases the female may not release her eggs. Here are a few reasons why.
· The pond is made up of all female Koi.
· The male Koi in the pond is not old enough to mate.
· The Koi is sick and not carrying eggs.
A sure sign that the Koi is sick and not carrying eggs is the scales. If the scales are sticking out or if the eyes are popping out it could be dropsy. This is when the kids are failing. You can use a salt dip to help the sick fish. Put 1 level cup of salt in a bucket with 5 gallons of water. Put the fish in the bucket for 1-2 minutes and then return it to the pond. This should be done 2 or 3 times weekly until the swings goes down. Another possibility is that a tumor is causing the swelling. This would cause the Koi to not swim properly.
Possibilities of what can happen if the Koi does not spawn (mate) and she is carrying eggs are listed next.
1. If the Koi does not spawn the eggs can remain in the koi for several seasons until she does spawn.
2. The eggs can be reabsorbed. This means she will just make them disappear back into her own body.
3. Sometimes the eggs can become egg bound. Egg bound is when the eggs rot and this will kill the female Koi.
Not feeding the fish in the winter will help the female Koi to reabsorb her eggs if she did not spawn in the spring. You really want her to reabsorb them as this is safe for your fish. You want to keep your Koi from having the eggs become egg bound.
To determine if your Koi are all female you can feel their head. A male's head will feel like sandpaper and a female ready for spawning will be slippery. If you can manage to touch each of your fish you will know their sex. If you find that you have a male Koi then he may not be mature enough to mate. Then again, maybe your Koi is just being picky.
To sum this up, if your Koi is fat and the scales are OK then probably you have all females or the males just are not old enough for mating. Not feeding your fish in the winter will help the koi reabsorb her eggs. Be ready to watch for baby Koi next spring.