Koi breeding and selection technology

The original Koi carp was a red carp. As early as 200 years ago, the Japanese discovered the color variation of this carp. After artificial breeding and improvement, it gradually formed a large-scale fish with great ornamental value. Because of its bright colors, brilliant specks, elegant posture, and beautiful posture, Koi is popular with people. Aquaculture enthusiasts very much hope that they can breed valuable varieties, so it is very important to understand and master the techniques of breeding and seedling breeding of koi. 1 broodstock selection
1.1 Identification of male and female koi Koi in the breeding season is easy to identify, in the non-breeding season, as long as experienced people can identify the male and female from its form, swim position and so on.
The body is short and full, the head is slightly narrow and long, the body is long and the head is short.
The abdomen enlarges, especially during the breeding season. The forehead protrudes slightly.
The pectoral fins are rounded at the end of the pectoral fin. During the breeding period, the pectoral fin ends of the female body are narrow and pointed. During the breeding period, the pectoral fins do not have “star hunting”. The first fins and lids have milky white protrusions, which are "chasing stars," and they feel rough with their hands.
Reproductive holes flat and flat, slightly protruding, after the reproduction period with a small and concave, after the end of the breeding period, gently press the hand and gently press the abdomen with the outflow of eggs. The abdomen has milky semen outflow.
Swimming is slow and unresponsive. Active and playful, especially during the breeding season, often actively chasing females.
1.2 Selection time and conditions of broodstock In North China, the Koi carcass which was kept as a broodstock in the previous year passed through the winter, and was moved to an outdoor fish pond in late March of the same year (the southern part is mostly at the end of February and early March). That is, we must do a good job of broodstock selection in order to obtain excellent offspring.
In order to cultivate high-quality Koi, as a broodstock for reproduction, we must first be physically strong, have no defects in the integrity of the limbs, strong colors, bright and shiny, such as white to be white, there must be no stain on it, dark spots of black matter should be dark Strong concentration, do not disperse or uneven density; markings are clear and to balance, body shape should be coordinated, body height ratio is 1:2.6 - 3.0 is better, beautiful swim, species characteristics are clear and clear, etc. . Secondly, it is better to select the appropriate Koi family of pro-fish strains based on the principle of mating and breeding high-quality and new varieties in the same variety of different water systems or different varieties.
1.3 Age of broodstock and proportion of male to female In China, the age of gonad maturation is 1-2 years, the first gonadal maturation, its reproductive function is not strong enough, the amount of eggs and eggs laid are not large, and hatched larvae are congenital There are many cases of stunting. If broodstock of this age group are used for a long period of time, there will be degradation of the traits of their offspring. Therefore, as the broodstock is the best choice of female 3 - 7 years of age, male 3 - 5 years of age, this age group of broodstock reproductive function, gonad full, large individual eggs, sperm motility, hatched larvae are also more physical it is good.
In order to increase the fertilization rate of the egg, it is necessary to ensure that there is enough semen volume, so the proportion of males and females for breeding is 1:2 or 2:3. If the number of male fish is not enough, it can be 1:1, but attention must be paid to both. Body size, size and age must be equal.
2 Preparation before spawning
2.1 Spawning ponds and hatching pools Spawning pools can double as hatching pools. For ease of management, hatching ponds should not be large, fish ponds, tanks, and pools can be used; spawning sites generally use small cement pools or indoor. Simple pool. General cement pool specifications are 4m X 4m X 0.8m or 3m X 4m X 0.8m, water depth 0.4 - 0.5m; indoor simple pool construction method: with 4 specifications for 2 meters X0. A frame made of 6m wood planks or thickened plywood is placed on a smooth concrete floor with a double or triple thick plastic cloth or a single layer of plastic canvas with a water depth of about 0.3 meters.
After the spawning pool is ready, it must be completely washed and disinfected. If it is a new cement pool, soak it in clean water for more than 20 days before use to prevent the pH from being too high, and then wash it with clean water. Propagation water is good for water with a pH of 7.0-7.5 and low hardness, and the dissolved oxygen in water is kept above 4 mg/l.
2.2 Fish nests Koi eggs are viscous eggs, so nests should be added to the spawning pool before spawning to allow the fertilized eggs to adhere to them. The fish nests are made of aquatic plants (goldfish, agrocybe, foxtail, etc.), palm husks, soft and non-toxic chemical fibers, etc. The method of production: if water weeds are used, they must be fished 3 to 5 days before use. Remove dead litter, clean, wash with 1 g/m3 of potassium permanganate solution for 30–50 minutes or soak with 20 g/l of salt water for 20–40 minutes, sterilize and rinse with clean water, and Cut it into small pieces of 30 centimeters long, take dozens of them into a bundle, and use a rope to tie it at one end. Sprinkle it into a radial ring-shaped fish nest. Attach a small stone to it and hang it in the water. If palm husk is used, it must be soaked in water and cooked repeatedly until there is no yellow juice, and then sterilized and bundled. If chemical fiber is used, it can be made after washing, in the same way as aquatic plants.
3 Spawning and hatching
3.1 Personally cultivated will select the best male and female broodstock generally kept in separate ponds. During cultivation, feed 1 to 2 high-quality baits each day. The baits are made of red worms, leeches, and chironomid larvae to ensure the nutrition of the broodstock. Daily removal of residual baits and dirt at the bottom of the pond is necessary to keep the water clean. After about one month of intensive cultivation, the broodstock can reach the fullness and maturity of the gonads.
3.2 Spawning
3.2.1 Natural spawning In different regions of China, there are also differences in the breeding season of koi. In northern China, the breeding season for koi is from late April to early June, while in southern China it is advanced from late March to mid-May. When the water temperature is constant above 16°C, the broodstock will be cultivated in a ratio of 2:3 or 1:2 according to the proportion of males and females, and put into a spawning pool with green water environment for 2-3 days before the birth, each cement pool. Put broodstock 3 - 4 groups, indoor simple pool 1 - 2 groups. After the broodstock enters the pool, when it is found that the male fish begins to chase the female fish, and when there is a slow escort next to the female fish, the fish nest should be placed. The fish nest is hung on the two sides of the spawning pool and at the center of the water layer. A float is tied above the rope so that the nest does not sink. When females were found to actively receive male stimulation, they indicated that they were about to lay eggs. When the males are fiercely chasing the females, the females swim to the upper part of the fish nest and use the caudal fin to hit the water to wave and spawn. At the same time, the males also discharge the milky white semen, fertilize the eggs and fertilize the eggs to complete the fertilization process, and the fertilized eggs are attached to the fish. Nest. Most of the spawning activities are concentrated in the early morning from 4:00 to 10:00. The spawning amount of broodstock varies depending on the size of the individual. A broodstock with a body length of 30–40 cm can lay 200,000–400,000 eggs.
3.2.2 Artificial insemination Different breeds of the same species or different strains of male and female broodstock have large differences in individual sizes. If natural insemination cannot be performed successfully, artificial insemination can be used to improve and maintain the quality of the Koi breeds. A new breed of good quality.
In the breeding season, place the brooding male and female broodstock in the same pond, place an appropriate amount of fish nest, add some fresh water, and observe carefully. When males were found to be fiercely chasing females, they indicated that they were about to spawn and ejaculate. At this time, male and female brooders were picked up with pelicans and placed in white enamel trays to gently press the abdomen of female and male brood fish from the genital hole. The mature eggs or milky semen were flown out respectively, indicating that they had matured.
After the male and female brood fish are ready, artificial insemination can be performed. First take the female fish, one person with his left hand to gently grip the tail shank, so that it can not swing around, with the right hand gently hold the fish head, another person with his right thumb from the pectoral fin at the front of the ovary soft pressure female abdomen, that is, eggs from the genital hole Into the previously sterilized and cleaned white enamel pots, continuously squeezed several times until the basic emptying. Then use the same method to deal with the male fish, the semen quickly squeezed into the Shengba pot, add a certain amount of fresh water, and then use the clean feathers gently mix the eggs and eggs, fully mixed and quickly insemination. The entire operation process strives quickly and is completed in 2-3 minutes. If you are working outdoors, avoid direct sunlight. 5 to 10 minutes after insemination, siphon out the upper part of the water, and then rinse the fertilized egg 1 to 2 times with isothermal water, and slowly pour the eggs into the nest in the hatching container and allow them to hatch.
3.3 Post-harvest broodstock rearing After broodstock spawning, the male and female broodstock should be moved to the rearing ponds with the same water temperature as the original pool in a timely manner, especially precious species. Management of postpartum broodstock should pay attention to the following points: First, when separating male and female fish, changing the rearing containers, and cleaning and changing water afterwards, remove the larvae with water, so as to ensure that the fish with weak physique is no longer mechanically damaged. If wounded, apply an anti-inflammatory drug to the wound and place 2-3 g/m3 of nitrofurazone or 0.2 g/l of salt in the pool. Second, the quality of the water before and after feeding is the same. The difference in water temperature does not exceed 2°C. It is best to put the post-partum broodstock back into the original pond for repose. When retreat, the pool water should be fresh and often be filled with new water, and the sewage be drained in time according to the situation. Third, according to the appetite of the broodstock, it is timely to feed palatability and quality bait. General broodstock after spawning weak, poor appetite, feeding should be reduced. Spawn or eat less on the day of spawning, after the amount of food for the usual daily feeding amount of 1/2 - 1/3, and to feed high-quality live red worms, snails and other bait to help their rapid physical recovery, to be their basic physique After normal recovery, it can be managed by normal feeding techniques.
3.4 Incubation Sterilize, wash, and inject water for incubation. Water for incubating is best to use unpolluted river water, well water, tap water, etc., of which the best is to store tap water for more than 2 days. When the water temperature is close to the spawning water temperature, put it into a sterile fish nest. The general depth of 25-30 cm, 6-8 fish nests per square meter; if hatched larvae to juveniles in a stage to be cultivated in the container, put the nest density to reduce to 3-5 One. The length of incubation time is closely related to the water temperature. It needs 5-7 days at a water temperature of 18°C, 3 to 4 days at a water temperature of 22°C, and 2 to 3 days at a water temperature of 25°C. According to the author's practice, the water temperature is controlled within the optimal range of 18 - 24°C, the hatching time is controlled within 3 - 4 days, the deformity rate is less than 5%, and the hatching rate is as high as 90%. The hatched larvae have the best constitution and The highest number of quality fish.
When hatching, the first thing to do is to remove the milky white unfertilized eggs in time to prevent water pollution. Second, pay attention to the rapid changes in water temperature and avoid direct sunlight. At the same time pay attention to changing the water regularly to ensure that the water is fresh, conditional available aerobic pump oxygen.
4 Seed breeding and breeding
4.1 Frying the fertilized eggs After 3 to 7 days of incubation, the larvae do not eat or move. They rely on the absorption of the yolk of the abdomen as a nutrient. Three days after hatching, the yolk disappears. The larvae start to swim freely and open up to take in the outside world. Food, at this time, began to feed live rotifers, paramecium, amoebae, and unicellular algae. If you lack live bait, you should feed the cooked egg yolk. Feeding method is: wrap the egg yolk with two layers of gauze and chop it, and then gently wrap the gauze on the surface of the water in the fish nest and the pool, so that the yolk particles are suspended in the water through the gauze pores and evenly distributed in the water for larvae. Feeding. It is usually fed once a day, and it is advisable to feed the amount of bait within 1 hour after feeding. In order to maintain clean water quality, it is necessary to timely clean the eggs when throwing eggs. 7 - 10 days after the larvae grow to more than 1 cm, remove the fish nest, feed the small fish, large rotifers, etc., the fry pool should continue to keep fresh bait. When the fry grows to 2-3 cm, it will be changed every 5-7 days. When adding water, it should be added slowly along the vessel wall to avoid damaging juveniles. The bait can be mixed with leeches, yellow larvae and palatable granules. Food.
4.2 Seedlings breeding seedling breeding process is actually a process of choosing the best, the preferred seedlings generally larvae within 3 months after hatching 3-4 times.
The first selection took place within 20-30 days after the hatching of the larvae. The body length of the fry reached about 3 cm. Mainly selected to stay in a sturdy body, lively swim, spine straight, the fins are not deformed or defective, individuals with distinct characteristics. Other individuals are eliminated or separately cultivated for sale. However, the species has different growth rates and the time for forming stripes is not the same. Therefore, the characteristics of varieties will appear sooner or later. For example, Showa's tricolor Koi begins to show its appearance about 15 days after hatching, and gold Koi appears about 50 days after hatching.
The second selection starts around 20 days after the first selection. The selection criteria is whether the fins are beautiful, especially whether the pectoral fins and the head shape are symmetrical, whether the eyes, kisses, and tentacles are deformed, whether the colors are bright, and whether the pattern markings are clear. Variety characteristics are obvious and so on. The third choice and the second choice interval are about 20 days. Selection criteria: the proportion of fins should be appropriate, the color is bright, the white background should be white, there should be no stains, the erythema should have clear edges, the dark spots should be dark and even, the stripes should be balanced, if there is a white part in the snout and tail shank , Variety characteristics are obvious and so on.
The fourth choice is basically the same as the third.
After the above mentioned 3-4 selections, generally only 1000-3000 or fewer of the offspring that are bred by each fish are required to meet the requirements.

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