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Catfish farming technology overview
Wang Yutang National Aquatic Technology Extension Terminology From a technical point of view, it is much easier to develop carp and carry out large-scale artificial breeding than carp and soft-shelled turtle. If cheap feed is available, the feed conversion rate is high, the cost of culture is low, and the added value of catfish farming is large. The carp is a good breeding species with strong adaptability and strong disease resistance. (I) Artificial propagation It has been reported that the types of artificial reproduction studies that have been carried out in various countries in the world are mainly small larvae, gills, scorpionheads, sinomenords, Russian storks, Chinese sturgeons, European oystercatchers, Amur sturgeon, and Daphnis.鳇 and more than 10 hybrids. Choosing excellent broodstock is the key to artificial reproduction. Whether in natural waters or artificial breeding, the gonad development of broodstock is required to reach stage IV. If the broodstock is not fully mature, it can be raised in cages or ponds or combined with injecting oxytocic agents to promote gonad maturation. The techniques of egg collection, insemination, detackification and hatching of squid in the process of artificial propagation are basically the same as those of squid, but the water temperature for hatching is more stringent. Generally suitable incubation temperature is 15 ~ 20 °C, about 7 days emergence. In case of sudden changes in the ambient temperature, incubation will be severely affected. (b) Breeding Seed cultivation of eel can be divided into two stages, the early stage and the latter stage. Pre-cultivation can be started from the disappearance of the yolk of the fry until the culture in the pond. The main foods are Artemia nauplii, aquatic oligochaete, copepods and other active baits, with the appropriate amount of egg yolk and artificial compound feed. In the later period, artificial feeds are usually used, and appropriate feeds such as small fish and shrimp can also be fed in appropriate amounts. In 1997, Russian scholars successfully researched two kinds of special feed for carp, which worked well. The main nutrient composition and content are shown in Table 1. Among them, OST-4 is suitable for the breeding period of 12-40g for pups; OST-2 is suitable for the breeding stage with the weight of more than 40g. In addition, foreign scholars have also developed many bioactive agents to promote the development of salmon. The use of a bovine pineal polypeptide agent abbreviated bpp10ppm concentration treatment of pups 8 to 20 days of age, the survival rate can be increased by 12% to 18%, and the treated pups can also eliminate or degrade the toxic effects of heavy metals. See Table 2. The test also showed that adding 2 mg kormogrizin and 0-2 mg vitamin C per kilogram of feed can increase the digestion and absorption capacity of the cockroach and increase the yield of the young cockroach by 10% to 45%. Treatment of pups with the following three biological actives can greatly improve the early embryonic development and the survival rate of pups: First, the peptide peptide solution SKB extracted from chicken plasma was used at a concentration of 400 mg/L, bathing fertilized eggs for 1 h. Survival rate of pups can be increased by 21% to 22%; Second, the use of Eneade extracted from yeast liquid, using a concentration of 5mg/L, bathing fertilized eggs for 1h, can improve the survival rate of pups 20% to 25% Third, the use of plant sterol Epine extracted from Yunzhi plants, the use of a concentration of 10-7mg/L, bathing fertilized eggs 1h, can improve the survival rate of pups 26% to 30%. (3) Cultivation of adult carp Breeding carp can be categorized into two types: small water bodies and large bodies of water. The former includes outdoor concrete pools, sinks, earth pools, canals, cage cultures, etc., which are generally intensively intensively cultivated and put on large scales. Specifications fish species, after feeding for about one year, the specifications can reach about 2 kilograms; the latter is stocked in lakes, reservoirs, mostly mixed with extensive care. The relationship between quality and stocking densities of four ponds reared with larvae One of the important tasks of industrialized rearing of carp is to obtain high quality fish. In order to meet the needs of fish farming in industrial farming, Russia is currently conducting high-density feeding experiments under pond culture conditions, with a stocking density of 15,000 tail/mu, which is the standard stocking density (0.5 to 10,000 tail/ 1.5 to 3 times of mu). This experiment was divided into seven groups with different stocking densities. The stocking densities were 5000, 6500, 8000, 9300, 10000, 12,000, and 15,000 per acre respectively. The rearing time was 40 days. It can be seen that the average daily growth can increase the stocking density. Affect the growth of young cubs. When breeding young pups in ponds, the amount of bait resources should be taken into consideration, and the stocking density should not exceed 120,000/ha. Second, the artificial breeding technology of Amur sturgeon, also known as Heilongjiang Ape, seven floats, is a large-scale economic fish produced in Heilongjiang. In recent years, cultivation has been carried out in northern China. (1) Breeding techniques (1). Selection of broodstock and identification of maturity The broodstock used for artificial breeding generally adopt naturally mature broodstock in Heilongjiang waters. The harvest time is the breeding season from May to July each year. The body was selected to be free from disease and injury, females weighing 15 kg or more, males weighing 20 kg or more, and aged 9 to 13 years old. The female reproductive interval of this fish female is 3 to 5 years. Non-reproductive male and female individuals have no obvious features. Male and female fish in the reproductive period are different, but there is no marriage color and starchaser-like secondary sexual characteristics. The specific identification method is: mature females who want to produce weight loss, kiss tip, spine tip, mucous surface, abdominal wall thin and soft, abdominal swelling and elastic. There was no significant change in body color and body shape of males, and individuals with body weights of more than 20 kg were mostly mature. During the inspection, see the tail of the fish bent into a "bow" shape, gently press the genital hole with semen out of the fish, this time the male fish can be used for breeding broodstock (2). Artificial oxytocin when the water temperature rises to 16 ~ 24 °C Artificial ovulation can be performed. When the water temperature is low, the oxytocin effect takes a long time. Lots of oxytocins use LRH-A. The method of injection and the dose used depend on the maturation of the broodstock. The basic dose is 60-90 μg per kilogram of female fish. Generally, the index of oocyte polarization reaches 1/30 or more, that is, production can be induced during the middle period of IV. All oxytocin doses were divided into two injections, 10% of the first injection dose. When the polarization index reached 1/55 or more, the remaining dose was injected. Males use half of the female dose and are injected when the female is injected for the second time. Males with better maturity can also be injected. The injection site is generally the base of the pectoral fin. After the bred broodstock, the male and female are raised in separate pools and stimulated by running water. Observe the activities of the broodstock and regularly check the changes of the fish. Females swim actively when they start ovulation, and frequently hit the water surface. Examination reveals obvious signs of flow in the ovary. The abdomen is gently pressed to the germinal hole where there are granules flowing out. At this point, the eggs can be taken. The time for taking eggs can be controlled within 90 minutes and no more than 150 minutes, otherwise the fertilization rate will be affected. From the relationship between time and water temperature, when the average water temperature is 16.5°C, the effect time is 18h; when the average water temperature is 19°C, the effect time is about 11h. (3). Egg collection and insemination Semen collection was performed by extrusion. Individuals weighing 20 kg can discharge 30 mL of semen at a time or even more. Male fish can be used many times. High quality semen is pure milk. Ovum was collected by laparotomy or hand push. An individual with a body weight of 15 kg can lay eggs 2.5 to 3.5 kg, and about 90,000 to 120,000 capsules. Semi-dry artificial insemination. The amount of semen used was 10 mL per kilogram of fish eggs. When using semen, dilute it with sterile water. The dilution ratio is 1:200 for semen to water. When insemination, the semen is put into the fish eggs and evenly stirred for 3 to 4 minutes, so that the sperm and eggs are fully combined, put it aside for a while, and the waste water is discarded and rinsed. The eggs of A. sibiricus are sticky. Generally, they appear viscous 5 to 6 minutes after fertilization and reach maximum viscosity within 15 to 18 minutes. Therefore, the eggs must be de-adhesive before hatching. Detackifiers use talcum powder or fine yellow mud. The former was made into a 20% aqueous solution and the latter was made into a 10% concentration. When debinding, the aqueous solution is poured onto the fish eggs and stirred continuously so that no agglomeration phenomenon occurs. When the fish eggs are all in the form of dispersed particles, the agglutination phenomenon no longer occurs when it is left standing, ie, the debindering effect has been achieved. Detacking time generally takes 30 ~ 60min. Fertilized eggs can be hatched after de-bonding. (4). The eggs of the hatching owl are larger and heavier, about 40,000 grains per kilogram. Hatching is best done under microfluidic conditions or by timing the eggs. The special special incubator specifications are generally 380cm65cm30cm, there is a drainage system and timing dial device, and can incubate 400,000 grains of astragalus at a time. The water intake at the time of hatching is 50 to 60 L/min, and the automatic egg dispensing device is once per minute, and the hatching rate is about 85%. In addition, two-layer cages can also be used for hatching. The cage size is 80cm60cm50cm, and 1kg eggs are hatched each time. The method is to float the cage fixedly on the river bay where the water quality is clear and the flow rate of the water is 0.8-1.5m/s. The egg is flipped every 20 minutes and the hatching rate is also about 85%. The incubation temperature is 16 to 24°C and the optimum temperature is 19 to 22°C. In this range, when the water temperature is high, the film emerges early and the seedlings are concentrated. When the water temperature is low, the seedlings emerge late, and the emergence time is long. At an average water temperature of 17°C, a film was formed at about 105 hours; at an average water temperature of 21.5°C, a film was formed at about 81 hours. The newly hatched larvae have a body length of 1.1 to 1.3 cm. After the incubation of 70h21°C, there was a defect that allowed for a swim. (B) seed cultivation techniques (1). Cultivation of fish ponds can use outdoor ordinary cement pool, single pool area of ​​about 300m2, depth of 1.5 ~ 2m. It is best to use well water that meets the water quality standards of the fishery. Clear ponds and disinfection of ponds before cultivation. (2). Stocking specifications are body length 18 to 30cm, weight 50 to 90g. The specifications for stocking in the same pond should be neat, uniform in size, and fry with different specifications should be kept in separate ponds. Stocking density is 0.5 to 1.0 tail per square meter. Fish were soaked with 5% saline before entering the pool for 20 minutes and were fed the next day after entering the pool. 3. Feeding can be used for domestication of bait at the initial stage of feeding, and gradually changed to artificial compound feed. The content of artificial compound feed was: crude protein 37.82%, crude fat 5.96%, crude fiber 8.48%, ash 14.91%, nitrogen-free extract 20.55%, moisture 12.28%, Particle size 2.0 ~ 3.0mm. Feeding 3 times a day, the daily amount of feed is 2% of the fish's weight. 4. Keep the water level over 1~5m during the breeding period, water temperature below 26°C, dissolved oxygen 6mg/L.