How to breed Koi fish? How to breed Koi fish in Vietnam? This is the primary concern of Japanese carp breeders. If you are new to farming, you will not be able to have good breeding techniques for Koi fish. Need to learn a lot.

This is a type of aquarium fish that is being loved by the aquarium community. However, many people fail to raise them. Especially in how to breed Koi fish. If you want to avoid the risks of breeding Koi fish, do not ignore this article of Petsate.

Reproductive age of Koi fish

As for the breeding technique of Koi fish, many people will have questions like when will Koi fish give birth? Are there any mandatory conditions? Under normal growing conditions, males are 2 years or more. Female fish from 3 years or more is the right age to start spawning. The reasonable breeding period for male fish is between 3 and 6 years old. Females are between 4 and 10 years old.

How to choose brood fish?

In order to improve the quality and efficiency of breeding Koi fish, it is necessary to know how to choose broodstock. Not only strict requirements on appearance, but also pay attention to the health status of Koi fish.

When choosing brood fish the best is to choose beautiful Koi fish , physically strong, full, smooth, scales are shiny. Especially no defects, no injuries, no diseases.

• For female fish: Turn the fish upside down, choose the big belly, the belly skin is soft, the genital opening is swollen and pink, the eggs have a high degree of looseness.
• Male fish: choose those with milky white semen, check by gently stroking the abdomen near the genitals. However, do not stroke many times because the fish will lose a lot of semen, affecting the fertilization rate.

Techniques for raising fish to spawn in a cement pond

The spawning tank is a cement lake, the bottom is flat and there are no sharp objects. The area is 2.5 x 5 x 1.2m, spread the net around the inside for the purpose of easy collection of broodstock after spawning and convenient for monitoring the spawning fish.

The initial water level in the spawning tank is about 0.5 m and must be collected 2 days in advance. Koi carp Japan is a fish that lays eggs on aquatic plants, so the medium is very necessary.

You can choose to clean water hyacinth, cut off the old leaves and roots to create a airy root cluster. Should choose 30cm root part, 20cm stem is best. Soak in 5% salt water to disinfect, remove other parasites.

How to breed Koi fish through diet

The technique of breeding Koi fish is very important in the choice of food. Food for breeding Koi fish ensures 35-40% protein. Fertilize periodically to create a natural food source, the amount of fertilizer depends on the color of the water, and composted manure must be used.

Amount of food: 5 – 7% of the total weight of the flock, which can be changed depending on whether the climatic conditions are favorable or not or depending on the health of the fish.

How to breed Koi fish with the right temperature

Under normal conditions, April – May every year is the best spawning time for Koi fish. During reproduction, it is required to control external conditions well.

Specifically, breeding techniques for Koi fish need to pay attention to such as temperature, water quality, pH level … but also requires the correct male-female ratio.

When the water temperature is normally stable at 18°C ​​or more, both male and female fish can be caught in a 1:2 ratio and released into a pre-prepared aquarium. When placing brood fish, it is best to arrange a sterilized nest in advance, to let them lay eggs naturally.

Usually when the water temperature rises to more than 20°C, the broodstock begin to spawn in large numbers. The time of laying usually starts from about 4 am – 10 am. Or stop at noon. However, there are times when it will also spawn at 17°C.

The eggs will now converge into a circle to form an “egg”. The generation after the eggs hatch, the color pattern will be relatively simple. The odds of spawning good quality fish will also be very small.

The technique of breeding Koi fish also needs to pay attention to weather factors. When the time changes will also affect the quality of reproduction. When the water temperature drops rapidly, the fish will stop laying eggs.

If you find that the edge of the egg nest is full of eggs, you must take it out and change it to a new nest. After the whole process is completed, take out all the eggs and put them in the incubation tank. Avoid being swallowed by the brood.

How to breed Koi fish with the most suitable density

Density, the ratio of males and females participating in spawning is on average 0.5 – 1 kg of female fish/m2 of spawning tank (about 2 females/m2 of spawning tank). The ratio of male and female participating in reproduction = 1.5/1 to 2/1 to ensure the quality of fertilized eggs.

The selection of broodstock is usually carried out in the morning: 8 – 9 am, when the broodstock are selected appropriately, the fish are brought to the spawning tank, stimulated under sunlight.

How to raise Ko fish i spawn best with average illumination on the lake of 8/24 hours. In the late afternoon, 16 – 17 o’clock, put the substrate in and create a slight flow of water into the lake. Arrange an aeration system to increase oxygen. Sun exposure and current generation or oxygenation are factors that stimulate fish reproduction.

Techniques for breeding Koi fish for beautiful colors

In how to breed Koi fish, it is necessary to pay attention to color. Should not be coordinated arbitrarily and in the following relative directions. The technique of raising fish to get the right color is as follows:

• The broodstock fish have yellow or silver brocade color for their own reproduction and do not mix with other colors to get a generation of fry with the same main color as the parents.
• Relatively two-colored brood fish on the body, red, black or white, black or red, white, are spawned with fish with three colors red, black and white.

Reproductive activity of Japanese Koi carp

The fish brought to the tank as above will spawn the next day, around 4-5 am. If the fish has not spawned, it must be rearranged from the beginning and continue to use the same stimulating factors as the original.

Similar to goldfish or common carp, before spawning, there is a phenomenon of male fish chasing female fish. Under the stimulation of new water, fish chase each other from the outside and huddle in the spawning nest, the speed of chasing is increasing, the fish will spawn easily.

The female fish vigorously sprays eggs, the male fish will fertilize where the eggs have just been released. During spawning, the male always follows the female to complete the spawning process.

For the case of fish not spawning, it is necessary to remove the media at about 9-10 am the next morning, reduce a part of the water in the lake, continue to let the fish dry in the sun until late afternoon to add new water. to stimulate the fish to continue spawning and add media. Create the same environmental conditions as the first time, the next day the fish will spawn again.

How to raise Koi fish to spawn in the incubation period

Regularly let the water flow gently or replace part of the water in the incubator with the stored water. The ovary is always aerated continuously, especially the eggs that are about to hatch. Avoid direct sunlight.

After about 24 hours, the fertilized egg will see two tiny black eyes. Embryo development requires a very high amount of oxygen, especially before and after the eggs hatch. As the fish’s body transitions from a stationary embryonic state to an active state, metabolism increases.

On the other hand, enzymes secreted to break egg-membrane bonds only work in oxygen-rich conditions, if oxygen is lacking, enzymes are inhibited leading to low hatching rates.

In the Koi culture technique when the fish is just hatched, the fish is easy to die in mass if there is a layer of scum on the surface. Due to the lack of oxygen, aeration must be increased after the eggs hatch.

How to breed Koi fish during the nursing period

Newly hatched fish feed themselves with yolk sac within 3 days. Fish from 3 days old fish eat plankton, soybean meal diluted in water. After this period, some fish will show color but not yet clear.

How to raise Koi fish to breed after 7-10 days, you can release the fish into the pond. The pond was prepared and well colored. A natural food source in a Koi . aquarium plays a very important role at this time.

The survival rate of fry depends a lot on how skillfully the Koi fish is raised or not. Pay special attention to natural food sources. The fry rearing pond needs strict management of trash fish sources (killing trash before releasing fry, strictly managing water in and out of the pond through culverts, caves, rain, overflowing water…).

After releasing into the pond for a few days, the fish can learn to eat mixed bran, gradually increasing the amount of food. The most important technique of breeding Koi fish in the nursery period is monitoring and managing water color. Always keep the water green, the pond is always well ventilated, the pond surface is drafty.

Depending on conditions, the water can be changed 2-3 times/month. To prevent fish diseases, it is necessary to fully comply with technical requirements from the process of preparing ponds, spawning tanks, rearing broodstock … to the management of the nursery ponds.

When the fish is about 4-5 months old, the period begins to develop, the fins according to the shape and color of the fish can be harvested for sale.

The saving in the technique of breeding Koi fish

Before putting in the incubator, it is best to drop some female duckweed to make a place to park the fry. At this time, the newly hatched fry will not eat or move. Mainly will rely on the nutrients in the egg yolk sac. This is the energy that sustains life.

Normally, 3-4 days after the fry hatch, they will absorb all the nutrients in the egg yolk sac. Then start swimming in search of food. At this time, the fry can be put into the fry tank for culture.

Techniques of breeding Koi fish require a scientific combination of stages. All the processes from fish selection to spawning are very important. Do not ignore any factors.

Hope the above knowledge about breeding Koi fish farming techniques will help you. Good luck!