Siniperca chuatsi is a fierce carnivorous fish belonging to the genus Falconidae, also known as mandarin fish and seasoned fish. The squid is renowned for its tender and delicious taste. The freshwater fish treasures are widely sold at home and abroad. As the amount of natural resources is decreasing day by day, the carp caught cannot meet the market demand. Artificially cultivated carp has developed rapidly, especially domesticated transfer food technology experiments (from feeding live bait fish to feeding chilled fish to full food intake. The success and promotion of feedstuffs have further promoted the scale of artificial breeding of carp. The species of farmed salmon in northern China are mainly natural seedlings harvested from reservoirs and artificial seedlings purchased from the south. Due to the fact that the number of natural seedlings can not meet the production needs, the actual production of carp seedlings in recent years has mainly been the purchase and transportation of artificial breeding seedlings from the south. However, the purchase and transportation of seedlings from the South has the problems of low survival rate for transport and rearing, easy introduction of foreign diseases and pests, and high production costs. It is very necessary to carry out artificial propagation of eel seedlings in the northern region. Now we combine our practical experience to artificially propagate the eel in northern China as follows.
1 Selection of broodstock In the natural environment, the big eyelid breeds at a later time than the pupa, and its growth rate is also slower than that of the pufferfish. Therefore, the broodstock should be selected as the broodstock. Under natural conditions, Amorphophallus can incubate from birth to ability to lay eggs. Males need 1 year, and females need 2 years. Selection of broodstock should be carried out 8 to 9 months before breeding, ie 1 year before breeding. It can be selected from lakes and reservoirs in the area, and can also be selected from ponds or cages where squid is raised. It can be selected from carefully cultivated pools. However, do not use the same source of female and male fish for long periods to prevent inbreeding from causing degradation of disease resistance and growth rate in offspring. When choosing specific broodstock, pay attention to the following six aspects:
1.1 The shape of the body of the mouth is a diamond-shaped body. When choosing a broodstock, the principle is to use the principle that the larger the vertical distance from the back to the abdomen, the better.
1.2 Body color The color of the mouth beak is yellow-green. The body color of the big eyelid is bronze (yellowish brown). Therefore, it is necessary to select the yellow-green beak, even if the big-eyed person is not big enough.
1.3 physical requirements without injury, no residue, no disease, no parasitic parasites on the surface, but also to choose a fat fish, the more fat the better.
1.4 The body weight of Cyprinidae grows fast, and the fry can grow to about 0.5kg at the end of the year. Individual large individuals can grow to more than 1kg. Therefore, the choice of female broodstock to choose more than 2kg individuals, select the male broodstock should also choose more than 1.5kg. Of course, it is best if the body length of the male and female broodstock is not much different.
1.5 Male and female identification of juvenile salmon is relatively difficult to distinguish male and female, after sexual maturity, especially in the breeding period, male and female individuals are more easily distinguished. Female fish: The mandible is rounded at the front end, not exceeding the maxilla; genital pores appear as a “one†shape, between the anus and the urination hole, pink; abdominal swelling, soft and elastic, lift the tail, visible on both sides of the egg , gently press the abdomen by hand, there is a little gel-like liquid and light yellow egg outflow. Male fish: Mandibles are sharp-angled, exceeding a lot of the upper jaw; abdomen with 2 holes, genital hole and urinary tract combined with 2 as a venthole, after the anus; light pressure mature abdomen of the male, milky white semen outflow, natural after entering the water spread.
1.6 Male-female ratio The broodstock selected are more males than females, and the ratio of female to male is preferably 1:2. If males do not meet the required number, the male to female ratio can also be reduced to 2:3, but at least not less than 1:1.
2 After the broodstock has been cultivated for the first time in the winter, it is necessary to strengthen the cultivation of the selected broodstock so that their gonads will develop better, mature earlier and produce more eggs. You can adopt a single pool or raise the broodstock in a broodstock pool.
2.1 The special pool cultivation pond should choose a pond with an area of ​​1000-2000 square meters and a water depth of 1.5m. It requires less silt at the bottom of the pond, adjacent to the water source, spawning pool or the hatchery ring. It is convenient for drainage and irrigation, and it is equipped with aerators. There is a long flow of water into the pool, the water is fresh and pollution-free, the transparency is high, and the dissolved oxygen is sufficient. The best edge of the pool is to plant watery plants such as eye dish, water hyacinth and water peanut. Two weeks before the broodstock entered the pond, clear the pond, dig out too much silt, dredge the inlet and outlet, reinforce the pond rake, and clear the pond with quick lime according to the conventional method. After 7-8 days, you can test the fish and put the fish. Put squid broodstock before, put 150 ~ 200g per 667 square meters of water on the surface of 500 to 700 tail of a large carp, feed pellet feed every day, so that big squid spawned hatching fish for squid broodstock feeding. A few days after the squid was put in, put 70 to 100kg per 667m2 pond (depending on the condition of the water source) and select the squid broodstock. The daily management during the cultivation period is mainly feeding, flushing and patrolling ponds. The bait fish has the best ground fish such as small bonito and small bonito. The wild fish and other wild fishes are the next best, and the bonito and bonito are the second. Before the small carp hatches, small live fish are properly fed. When the small carp grows in the pool, feeding is stopped. However, before the spawning, two bait fish are fed, feeding about 100 kg per 667 square meters. The stimulation of water flow is very important for the development of gonadal gonads. After the spring in the still water pond, select sunny days to drain part of the old water and inject new water. After changing the water, the water level should be lower than the original water level, and keep about 60cm of shallow water so that the exposure can rise rapidly. Water temperature. After flushing water once a week, when the water temperature rises above 20°C, the frequency of water changes will increase to 2 to 3d1 times, and the water level of the pool will be increased by about 10cm each time. Flowing pond cultivation is better. In addition, we must stick to the morning, mid-night and evening patrols to observe the water quality, fish movements, and feeding conditions to prevent and treat diseases and prevent floating heads. When the water temperature is above 20°C, it is necessary to watch the pond at night, especially in the rainy and sultry days, and it is necessary to pay more attention to it and find that the floating head is in time for increasing oxygen.
2.2 Coupling In order to reduce the cost of broodstock broodstock cultivation, we use grassy fishes, clams, breams, and other home-breeding fish ponds to raise squid broodstock. The broodstock of the family fish is relatively large and will not be harmed by squid broodstock, and the amount of fish contained in the pool is low, and a certain amount of wild fish is available for feeding. When cultivating, put 40 to 50 squid broodstock and 10 to 20 kg bait fish per 667 square meters. At ordinary times, the patrol pond should pay attention to the observation of the amount of small fish. If it is found that the quantity is insufficient, appropriate additional feeding is required. The baitfish is generally used for pupa and bream. During the doubling period, flush water regularly, 1d1-2 times, about 1h each time, and keep the same amount of water and water. Carp broodstock prefers live water, and it is best to keep microfluidic water in places where there is sufficient water. During the hot summer season, we must often visit the pond to prevent floating heads.
3 Before preparing for breeding, you must first prepare the necessary equipment and articles.
3.1 Equipment disinfection Scrub, disinfect the spawning pool and incubator equipment, dredge into the water outlet, plug the hole in the pool wall, and prepare to eliminate the poisonous strainer and the harvested cage. The propagation equipment includes stretchers, washbasins, hand towels, syringes, needles, mortars, feathers, measuring cylinders, beakers, thermometers, buckets, glass jars, etc. used for the transport of broodstock and injections, all of which are cleaned, disinfected and sterilized.
3.2 Incubation Water It is best to use well water for incubating and use water before use. The river water and the pool water should be thoroughly disinfected with bleaching powder of 20mg/L 1 week before use, and filtered with a sieve.
3.3 Oxygen production drugs Eel production uses 3 kinds of drugs: the pituitary gland, chorionic gonadotropin (HCG) and luteinizing hormone-releasing hormone analogue (1RH-A) of salmon or trout. Can be used alone, can also be mixed, mixed use better.
3.4 Prepare a sufficient number of mature group head broodstock to spare.
4 artificial labor
At the end of May or early June, when the water temperature stabilizes at 24 to 26°C, artificial oxytocin production can be performed. The method is the same as that for home fish and the injection method is better for body cavity injection. Two injections are commonly used in production, ie, the first injection of 20% to 30% of the full dose of the oxytocin in the female, and the rest 8 to 12 hours after the injection, while the male is injected once in the second injection of the female. . In order to grasp the time, both female and male fish can take two injections. Injection dose of female fish per kg body weight of HCG1000 ~ 1400IU + pituitary 1.5 ~ 2mg, or pituitary 5 ~ 8mg + LRH-A50 ~ 100μg, male fish halved. After the injection, the broodstock was placed into the spawning pool at a male to female ratio of 1:2 or 2:3.
5 Spawning Fertilization After artificial oxytocin production, natural spawning or artificial insemination can be performed.
5.1 Natural spawning The natural spawning of salmon can be performed in the fish spawning pool, and the broodstock can also be placed directly in the hatchery ring. The spawning pool maintains a depth of 30 to 50cm and micro-flowing water. Place 1 group of brood fish (1 female 2 male or 2 female 3 male) every 3 square meters. The time from the second injection to the estrus and spawning time of the broodstock is about 20 h. When the estrus reaches orgasm, the male and female broodstock swim side by side, intertwined with each other, often splashing bursts of water, and after completing an oviposition they rest underwater. Soon afterwards chasing and copulating spawning is repeated, often repeated several times, for a duration of 3 to 6 hours. The method of egg collection is the same as that of home fish.
5.2 Artificial insemination The squid broodstock injected with aphrodisiac is maintained in a cage or spawning pool. After 10 hours, check once every half hour. Remove the female fish and gently press on the abdomen. If a piece of egg is produced, grab the genital hole immediately and prepare the male fish for artificial insemination. If the extruded liquid is a yellow liquid, it indicates that it has not matured yet. Then wait for a period of time to perform artificial insemination. Artificial insemination is the same as home fish.
6 Incubation of fertilized eggs of artificially hatched salmon can be performed by hydrostatic oxygenation or flow hatching.
6.1 Hydrostatic Oxidation Incubation This method requires oxygenation pumps, ventilation manifolds, fistulas, branch tubes, bubble stones and washbasins, casks or glass jars, and aquariums. One oxygenation pump is connected to the vent main, the branch pipe, and a dozen branch pipes. One pipe is equipped with a bubble stone sinking into the basin, wooden barrel or glass tank, and the bottom of the aquarium, and the fertilized eggs are evenly and sparsely sprinkled. At the bottom of these containers (avoid accumulation), note 15cm deep water. Continue to oxygenate the container. Change the water 4 times a day, morning, evening, night, and use a pipette to suck out dead eggs, unfertilized eggs, and infected eggs. This method is simple, convenient, and small in water consumption, but the hatching rate is lower than that of the flowing water incubator method, and scale production is not suitable.
6.2 Flowing water hatching Incubation of hatching rings, hatching barrels and hatching tanks for hatching of home fish can be used. We are using a self-designed plexiglass incubator (which has been granted a national utility model patent, patent number ZL 03284158.2) for excellent results.
6.3 Precautions during incubation 1 Keep fresh water for incubation, fresh oxygen, no pollution, and no predators. 2 Control the flow rate of water during the process of hatching. If the flow rate is too small, the hatching rate will be affected. The flow rate in the incubating cylinder is such that when the egg is flushed close to the water, it sinks again, and the water flow in the loop can be adjusted by a flow rate of 20 cm/s. When the fry is hatched, some flow rate should be accelerated slightly. After the yolk sac is absorbed (3 to 4 days after hatching), the flow rate should be reduced to allow the fry to swim freely. 3 Keep the water temperature. The normal temperature for hatching catfish ranges from 20 to 32°C, and the optimum temperature is around 25°C. Within this range, the higher the water temperature, the faster hatching. During incubation, attention should be paid to insulation. The temperature difference between day and night must not exceed 3°C. 4 dissolved oxygen. During the hatching of the fertilized eggs of the carp, and after the fish film is released, the dissolved oxygen is high. In addition to sufficient oxygen exposure for incubation, hatching water should also be aerated and aerated in the reservoir. 5 to grasp the appropriate density of eggs. About 20,000 eggs were laid per square meter in the incubating in still water, and the nesting density of the hatching ring was controlled to be about 300,000 eggs per cubic meter of water, and about 50,000 eggs were laid per cubic meter of water in the hatching tank. 6 to prevent water, power outages, fleeing seedlings and premature rupture of the membrane, to prevent sudden changes in water temperature and disease. Salmon eggs are prone to hydromycosis. Before the fish eggs enter the incubator, the eggs can be soaked in malachite green at a concentration of 60 to 100 g/m 3 for 3 to 5 minutes to prevent them. When the condition is found at a low temperature (below 20°C), the solution of malachite green is splashed in the ring to make the water slightly green. After the green disappears, it is splashed 1 or 2 times. 7 strengthen the film to the level of management. At 22 to 25°C, the fertilized eggs began to form in 32-40 h. The newly hatched fry has poor swimming ability, dragging a large yolk sac and not feeding. At this point, we must speed up the flow of water so that it will not be deficient in oxygen. After 3 days, the yolk sac basically disappeared, the fry could swim flatly, and the teeth grew up. They could ingest food. At this time, fry cultivation began.
7 Other Precautions (1) In order to obtain better reproduction effects, the same batch of broodstock that is produced by pueraria should not be too different in male and female individuals, and it is best to select individuals of similar size.
(2) At the same time of stimulating the production of squid, it is necessary to synchronize the production of oystercatcher so that the live squid can be eaten in time after the emergence of the squid.
Author: Henan Academy of Fishery Sciences, Nanwan Reservoir Fishery Station, Xinyang City, Henan Province
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