With that in mind let's get down to the basics!



The first thing you need to do is to determine the sex of your Koi. This is impossible to do until the fish becomes sexually mature which usually hapens when it gets to 10 inches or longer. Even sexually mature fish can be tricky to sex but in general a male Koi will be less plump than a female Koi because a mature female has filled ovaries that expand her body.

The sexually mature male Koi typically looks more slim and streamlined and often has larger and somewhat more pointed pectoral fins than the female. There are some exceptions to these general rules and it is possible to have a scrawny female or fat male Koi fish.

When Koi breeding season begins the male Koi will develop two white spots on his head and on the first rays of his pectoral fins. The breeding tubercles will look like small white elevated spots and can be hard to recognize. The Koi breeder sometimes becomes alarmed and treats their fish for itch when they notice the small white spots, but with practice soon learns to recognize them.

If you keep your Koi in an outdoor pond they will start to spawn in late spring and early summer as the water temperature begins to rise. A water temperature around 20 degrees Celcius or 68 degrees Fahrenheit is ideal to stimulate Koi breeding.

If you keep a lot of Koi together a so-called flock spawning will occur. A flock spawning will give you an abundance of healthy offspring but breeders try to avoid them because these fish often display less desirable colorations.

Thus, during professional Koi breeding, the fish keeper will select desirable parent fish and place them in their own pond. You will need one female and two to three males for a successful Koi breeding.

If you don't want to dig a new pond especially for Koi breeding you can use a children's swimming pool. To increase the chances of spawning you can change the water frequently and lower the water temperature somewhat.

Adult Koi eat live foods such as worms and flies and parents won't hesitate to eat eggs as well as free swimming offspring in their own pond! During professional Koi breeding when a large survival rate is important the eggs are best placed in their own ponds.

Collecting the eggs will be difficult if you let your fish deposit eggs all over the pond. Most breeders therefore use spawning mops. A spawning mop can be made from frayed nylon ropes or pieces of cotton string that are placed on the surface of the pond.

The breeding fish see the mops as floating plants and will most likely choose them as a breeding site.

During the Koi breeding you will eventually notice that the males are chasing the female. This behavior usually goes on for several days before any eggs are released.

When the females deposit their eggs at the spawning mop the males will immediately go over and fertilize them. The spawning mops can then be removed and placed in a fry raising pond.

As you can see, though it takes some preparation and attention it is not all that difficult to perform a successful Koi breeding.