Obscure Oriental? Scaled Artificial Propagation Technology

Takifugu obscurus (abe), belonging to the genus Odonata, Acipenser, Oriental, is commonly known as Pufferfish and is an important fishery resource in the Yangtze River waters. Pufferfish, as an extremely valuable luxury aquatic product, has a large sales volume on both sides of the Yangtze River. The current natural catch has far exceeded the market demand. In order to satisfy consumption and protect resources, the author has carried out research on the artificial reproduction and culture of Obsidus orientalis for several years in succession since 1995. It has now developed from the original experimental stage into a comprehensive and comprehensive development technology. This article is a comprehensive summary of the scaled artificial reproduction technology of the Obsidian Oriental Yutun. First, the collection of broodstock l. The time and place of collection are selected from the individuals captured from Nantong to Nanjing Section in March-April each year. Since this section of the Yangtze River is relatively moderate from the Yangtze River, the broodstock swim has been fully diluted and the gonad maturity is relatively good. 2. Physical fitness to determine the quality of pro-fish constitution is directly related to domestication and cultivation can survive and urge production success. The collected broodstock requires that the fish be normal, healthy, disease-free and harmless, lively but not indiscriminate, and the fins should be fresh and naturally stretched, and be quiet when they are naturally not tilted or suspended in water. Not swollen and turbid. Among the pufferfish caught by various fishing tackles, the best is the Zhangwang. Those captured by hook catching and gill netting often cause internal injuries and are not suitable for use. The female body is more than 0.6kg, and the male body is more than 0.5kg. 3. There may be at least two types of pufferfish that have been identified for reproductive migration in the Yangtze River, and there are more species at the estuary of the Yangtze River, and most of them are low-value river fish tuns. The economic value is not high, so we must strengthen the identification. It can be identified by its body color, markings, and dark spots. The dark-backed oriental fish tuna body is brown on the back, yellow on the side of the body, white ventral surface, 4-6 dark brown stripes on the back, upper rear of the pectoral fin, base of the dorsal fin, The pectoral fin bases all have dark spots, and the above characteristics are significantly different from those of oriental fish pufferfish and sea pufferfish. 4. The discrepancy between male and female of broodstock in pufferfish is not obvious. It can be judged by using integrated discriminant system by combining individual indexes such as abdomen, black spot, pectoral fin and swimming behavior. For the abdomen enlargement, the short and wide black spot on the back of the caudal fin, and the slow-moving individuals are mostly females. On the contrary, the abdomen is tight, the spots with dark spots on the back of the caudal fins are relatively narrow, and the agile individuals are mostly male. The ratio of broodstock collected was kept at 1:1--1.5. 5. The identification of gonad maturation of the broodstock is a guarantee of successful production of gonads. When collecting broodstock, special attention must be paid to its maturity. In general, females require abdominal enlargement, ovary outline is obvious, the size of the anterior and posterior abdominals is uniform, genital pores are loose and ruddy, the back and abdomen have small spines protruding hard, and the handle is harsh and stabbing hands; males require gentle pressure to have a small amount of semen out of the abdomen. If the abdomen is too loose, females that are as soft as cotton but inflexible and have a large genital hole must not be used. 6. The transport method uses nylon bags for oxygenation. After the desired broodstock is selected, press one bag and one end, and fill each bag with fresh water 1/3-1/4 and oxygenate. Shock absorbers (foam box) should be provided on the transport vehicle. The ventilation time should be more than 4-5 hours. During transportation, the water temperature in the bag must be basically stable. Second, the broodstock domestication and cultivation The handling and water quality conditions of the domestication pool require the domestication pool to be a cement pool with an area of ​​over 200 square meters, a water depth of 1-2 meters, a well-established intake and drainage system, and oxygen-enhanced equipment. The pool water is kept in a state of rapids all-weather. Two weeks before the release of fish, the concentration of chlorine dioxide was used to disinfect for 3 days. The harmful bacteria in the original water were completely removed, and the temperature was gradually increased to 20°C. The amount of dissolved oxygen required to reach 5mg/l, ph7.5-8.5; transparency 40-50cm. 2. The broodstock and the oxygen bag brought back by the domestication method are put into the human water. When the water temperature inside and outside the bag is the same, the oxygen bag is released to release the broodstock. If the broodstock has a slight injury, penicillin or malachite green should be injected to prevent infection. After the broodstock goes to the pool, there is a special person to observe the broodstock activities day and night, in particular, to observe whether there is foraging behavior in broodstock activities. If the broodstock can be seen to have obvious foraging behavior, then use the peeled quail meat to hang in the water for feeding at the designated point, and check the food intake at the same time the next day. Regardless of whether it is feeding or not, replace the leftover bait completely. According to the situation, proper water injection and drainage, to maintain the water quality conditions are relatively stable, and according to the temperature of the domesticated water temperature changes and broodstock activity, timely inspection of broodstock gonad maturity. Generally raised for 10 days and 15 days, until the broodstock to restore physical strength and gonadal development and maturation can be elicited. Third, elicit production 1. The urine-production condition urine production tank is a 20- to 100-square-meter cement tank. The oxygen is increased by the air pump, and the low-power small water pump continues to generate micro-flow. The water depth is about 0.8 meters, and the water temperature is controlled at 21 to 23 degrees Celsius. A batch of broodstock selected for appropriate oxytocin was transferred to the urine production tank 2 days before oxytocin production. 2. The oxytocin and dose of oxytocin were lhrh-a2, hcg, and pg. The combination of lhrh-a2 and pg is better. The injection dose was 3.5 mg pg + 60 μg lhrh-aykg, and the best effect was achieved with 3 injections. The injection interval was 12 hours. In practice, the injection dose should be appropriately increased or decreased according to the gonad development in the broodstock. 3. Pre-spawning inspection methods are crucial for determining the best spawn time for broodstock, and immature or over-matured eggs can make fertilization worse. Since oxytocin should not be disturbed, do not disturb after injecting the first and second shots. When the third needle is injected and within 10 hours to 15 hours of the effect time, attention should be closely followed, including broodstock swimming behavior and body color changes. Wait until the broodstock swims slowly, the abdomen no longer continues to enlarge, and the body becomes darker, then the egg collection and insemination should be promptly collected. If the abdomen has ooze out of the egg, the egg is light yellow, full and shiny after absorbing water, good elasticity, it is a good egg, the possibility of fertilization is high; if the outflow of the egg is slightly white, dull, poor elasticity And fragile, it is too cooked eggs. Due to the narrow range of optimal timing of fertilization for this egg, the broiler's estrus performance is not obvious. Little attention is paid to the fact that the ovum is too mature and the fertilization effect is poor. The inspection frequency must be increased in order to detect timely treatment. 4. Postnatal care of broodstock Care of broodstock after spawning should be a task that requires attention in production. During oxytocin production, especially when squeezing eggs, it can cause broodstock injuries. In addition, physical failure after oxytocin can cause broodstock to die if it is not properly cared for. After spawning, the finfish that have been over-fatigue after birth should be put into a pool of fresh water to allow them to fully rest and restore their constitution and enhance their resistance to disease. IV. Artificial insemination and incubation Artificial insemination methods commonly used wet insemination and dry insemination two methods. Whether the wet insemination or the dry insemination is finished, it is very necessary to rinse the fertilized eggs, mainly to remove excessive semen, ovarian fluid, blood stains, etc., to breed water-resistant mold. 2. The hatching method distributes the fertilized eggs well-dispersed evenly on the sticky egg plate or the hatching bucket placed in the hatching cage, and both the static water hatching and the microfluidic water hatching can be adopted. 3. Environmental factors affecting hatchery and hatching management The incubation of fertilized eggs is affected by a variety of environmental factors, including water temperature, dissolved oxygen, water quality, light, and predators, all of which affect the level of hatchability. The hatchery water requires do>6mg/l. Because the oxygen consumption of the embryos is large, the lack of dissolved oxygen in the water will cause embryonic growth retardation, stagnation, and even suffocation death. The water temperature can be controlled at 18°C ​​to 25°C, preferably 21°C to 22°C. If the amount is too high or too low, the embryonic development will be stagnant or unsound. Even if there is a small amount of emergence, it is mostly deformed freak, and most of them are in the middle of development. . The water quality requires fresh, clean, pollution-free and does not contain predators. The light intensity is better and the light intensity is better. 4. During the hatching process of the water mold, even if the fertilized eggs are rinsed cleanly and with proper water flow, water mold will still occur from time to time, and active measures must be taken to prevent and control them. In the first 2-3 days of the incubation period, the malachite green medicine bath was used 1-2 times a day at a concentration of 70x10-6g/l for 5 minutes each time. Can not be used in the film will be used for 2-3 days, otherwise it will cause damage to the fertilized egg caused by death of fertilized eggs or hatched abnormal seedlings. The water quality treatment machine can be used to control aquatic mold in the later period of hatching. It can stop for one hour every two hours to open, which can achieve certain mitigation effect. 5. Incubation time and embryonic development At a water temperature of approximately 22°C, normally developed fertilized eggs can hatch fry in 120-180 hours. Incubation time is negatively correlated with water temperature, so the water temperature can be adjusted appropriately according to the abundance of bait to extend or shorten the incubation time so as to ensure that there is sufficient food. During the incubation process, the fertilized eggs are sampled every 2 hours to observe the development and normality of the embryos. In particular, each major embryo develops. 6. Incubation of hatching fry in cages The newly hatched fry was extremely tender and weak, and there was no swimming ability. When the density of hatched fry is too high, it must be gradually transferred to other clean cages. Be careful when handling. At this time, the fry's physique is weak, and it is difficult to withstand dramatic changes in the external environment. It must be kept in a suitable cage for several days. The newly hatched fry is made of yolk and oil globules. After 2-3 days, the hatching sac is changed from big to small. The digestive system of the fry is further differentiated and can be used to feed. At this time, the 300-mesh filtered egg yolk should be fed. To reduce the number of times and more, and gradually mixed with 200-mesh filtered rotifer feeding, rotifers must be sterilized with lppm of chlorine dioxide before feeding. Feeding 10 times -12 times a day, the ratio of egg yolk to rotifer is 2:1. Holding cages to ensure adequate dissolved oxygen, but the amount of dissolved oxygen should not be too high to prevent suffering from air sickness, while ensuring that there is fresh water, if necessary, further separation. Generally must be kept in cages for 4 days to 5 days, fry larvae inflated, yolk sac basically disappeared, that is, fry can have strong swimming ability and active prey, consider hair pond. It is particularly important to shave the perimeter of the holding pool during temporary maintenance so that the water is dimmed and the light is even. Strong light or uneven light will cause the fry to gather in the light and keep moving. It will consume a great deal of energy, will be wasting and emaciated, and it will cause local hypoxia, which will be detrimental to fry. Fifth, seed cultivation The selection and clearing of the fry pool The fry pool we selected has the following features: It is convenient for injection and drainage, with moderate water depth, an area of ​​2000-40 square meters, rectangular, adequate amount of silt, water-free grass and abundant sunshine. After determining the fry pool, first drain the ground water, trim the pond, and then clear the pond with lime. 2. After cultivating the pacific fish fry's palatability bait bio-clear pond, 40-60 cm of fresh water is injected about 10 days before the fry in the pond, and the water is filtered with a 100 mesh cloth. In the 4 days before the fish seedlings in the pond, 3kg soymilk is splashed once a day. At this time, it is necessary to control the consistency of rotifer breeding to the peak period and the time of the fry. Ensure that the abundance of rotifers in fish ponds is lower than 10/ml. 3. After all the conditions for the stocking and daily management of the fry were met, select the sunny pond in the afternoon. After the fish fry under the pond, its daily management is basically the same as that of conventional fish. However, when the puffer fish reaches a size of 3 cm in the later period, it may be considered to gradually feed the compound feed for sale or move into the greenhouse for industrial breeding.