Spawning for Koi Pond

Koi are not livebearers but lay thousands of eggs in a single breeding. Koi must be at least 3 to 4 years old and of sufficient size before they breed. Koi require special water conditions and environment for breeding. This is maybe the most time consuming part of keeping healthy Koi. The eggs and baby Koi will need to be separated from the adult Koi or they will be eaten. Once eggs are laid, the baby Koi hatch in about 3 to 7 days depending on the weather. The survival rate for baby Koi is less than 50%.

Spawning will take place in the spring, after a colder winter, about the time when the water reaches temperatures of sixty degrees or more. They will attach the eggs to plant matter, or nest-like material. Some Koi enthusiasts have come to recommend a new rag mop head in for this use. The
consensus is that hatching in early summer (such as May or June) is best, because then the young hatchlings have time to grow and become used to their environment before winter comes to affect them.

Pregnant Koi are easy to spot. They are large with bloated eggs and their abdomen is heavy and soft. When the females are ready to lay the eggs, you can assume that the male is also ready. The female should never be out of water any time when netted or moved by hand. Mating fish must be handled
extremely gently. Some breeders put both male and female into their separate pond at the same time. Others put the female in early to give her time to adjust, and then add the male later in the afternoon or early evening.

Improvised tenting needs to be set up during the spawning. Some breeders like to use fishnet, while others construct a chicken wire tent/fence. The main point either way is to add additional shading. This is the equivalent of "setting the mood."

Spawning usually occurs in the early part of the morning, if nothing has taken place by noon, then chances are extremely high that nothing will happen the rest of the day. In this situation, the Koi can be lightly fed, given some attention, and made as comfortable as the situation allows. Keep careful
track of the water to avoid over-heating. Your Koi may refuse to spawn if the water is too warm or if the weather is overly hot. After three days, if there has been no action, they should be returned to the main pond because of the aforementioned danger of over-heating.

Afterwards, aside from the eggs being kept separate, the female should also be isolated in a separate pond, away from all males, to recover. Let her rest, but prepare to check for injuries later that could have been caused during the mating. The actual breeding pond will have a cloudy appearance and a distinctly unpleasant smell. Caution should be taken to keep the eggs moist at all times. Gradually the horrid smell will leave.

If you don't feel comfortable with a first spawning, find a Koi club, and they can help you prepare for this event.