Preferably the spawning pool is made of cement and the surface is plastered. This is to keep fish scales from being damaged if friction occurs during the spawning process. The size of the pool is varied, usually around 3 × 6 meters with a depth of 60 cm and a height of 40 cm. The pool must have in and out channels. In both channels, a fine filter must be installed. The goal is that there are no disturbing pests that enter the pond and spawning eggs or larvae are not washed out of the pond. Aside from that, make sure you don’t accidentally pour adult koi food there excessively so it won’t get dirty easily.
Before filling the water, the pond must be drained and dried first. The point is to break the cycle of germs that might be in the pond. The water used to fill the pool should be precipitated for 24 hours. Koi fish like to stick their eggs to the media in the pond. Therefore, provide artificial fish nest made from palm fiber or you can use water plants. This is for enriching the oxygen level of the aerator in the spawning pool.
The spawning process
Once the spawning pool is ready, insert the female koi broodstock first. Spawning usually takes place at night, so the female parent can be included in the afternoon. Let the female parent adapt to the conditions of the pond so they won’t feel stress.
After 2 to 3 hours, the male brood can be released in the spawning pool. The number of male brooders included 3 to 5 fishes. This is to avoid failure in spawning and all eggs released by female sires can be fertilized. Actually, it can only use only one male if the size of the male is quite large, but the risk of failure is higher.
Spawning usually takes place around 11 pm until early morning before sunrise. During that time the mating process will occur, where the female will spray her eggs at the artificial fish nest. After the egg sticks, the male brood will spray the sperm to fertilize the egg.
After the spawning process is complete, immediately remove the broods from the spawning pool.
Hatching of larvae
The eggs attached to artificial fish nest or water plants must be submerged in water. Therefore, you may give ballast to artificial fish nest. In normal circumstances, the temperature is around 27-30 degrees Celsius, and the eggs will hatch within 48 hours. If the water temperature is too cold the hatch will last longer. If it is too hot the egg can rot.
After the eggs hatch, the artificial fish nest or water plants can be removed.