At present, broodstocks used for artificial breeding are basically pond fish. If attention is not paid to breeding, the quality of seedlings will be seriously affected, and the germplasm will be degraded due to inbreeding. The main degradation traits are: body shape, body color and Standards are different; growth rate is slower than standard; growth and differentiation ratio is greater than 5%.
There are two main ways to ensure seed quality:
1. Choose a healthy broodstock. One year of sexual maturation of the bigmouth bass, when harvesting adult fish at the end of the year, individuals with a large body size (above 05kg/over), strong physique, and brightly colored fish should be selected as reserve broodstock to ensure the quality of eggs and ensure that offspring are not susceptible to germplasm. Degradation.
2, to avoid inbreeding. When broodstock is specifically selected, it is necessary to avoid the selection and retention of the same batch of offspring that were artificially propagated together with the parents. The female and male should be selected from different farms, and the source of the seedlings should be investigated at the same time. The geographical distance of different farms should be as far away as possible.
Second, innovation has proposed a number of measures for high-yielding aquaculture technology. 1. Stocking of large-sized fish species and seedlings is too small to achieve high yields. Only the stocking of large-scale species is to increase the survival rate and ensure high yields. In the initial stage of cultivation, the large-scale species are generally cultivated in a rough manner. After the fry are cultivated into 10-13 cm species, they are reared to a large area of ​​water for cultivation. In the roughing pool or in the cultivating pond, a corner is enclosed by a net, and the size of the area can be determined according to the aquaculture needs. The total area accounts for about 20% to 30% of the cultivated pond area. Clear pond water 50-70 cm, appropriate fertilization, cultivating water quality, increase plankton, transparency 25-30 cm, water green mung bean is better. After the fish fry under the pond, it first feeds on the zooplankton in the water, so it is necessary to maintain a certain amount of fat in the pool water. When the fry body grows to 15 centimeters in length, it should be domesticated in time to allow it to feed on fish flesh, and then gradually transition to chilled fish. Feeding adhered to a small number of times to meet the feeding needs of fry, make it consistent growth, avoid size differentiation, mutual residual food. With the growth of fish fry, the fish pond should be properly added with fresh water. Normally, water injection should be performed once every 5-7 days, each time about 10 centimeters of water injection, until the ideal water level, and later some water pools should be replaced according to the weather and water quality conditions.
2. It is an important technical measure to obtain high yields by properly cultivating fish and fish ponds with large populations of black oysters. The high-yield, large-mouthed, black pupa pond generally requires an area of ​​about 10 mu, a water depth of 20-25 meters, a mu fish rearing density of 3500-4,500, and a ratio of about 10% of the total stocked fish is suitable, and it depends on the cultured ponds. , water body, size, plan for adjustment, generally 11-
12 heads of carp 150 tails/mu, 03-05 ton/tail catfish tails of 65 tails/mu, 01-02 kgs/tail catfish tails of 30 tails/mu, other fish (eg oystercatchers, grasshoppers, etc.) Consider proper polyculture.
3, scientific feeding adhere to the "four set" principle to achieve qualitative, quantitative, timing, positioning feeding. When the water temperature is suitable, the weather is fine, and the water quality is fresh, the appetite of the bigmouth bass is vigorous and the feed is fed as far as possible to meet its rapid growth. The bigmouth bass generally uses chilled fish as feed. The chilled fish has rich protein content, but lacks vitamins. It should add appropriate vitamins properly, or use mixed feed to mix chilled fish at the same time to increase feed utilization and maintain balanced nutrition. Accelerate growth. Generally, the daily feeding amount of the seedling stage accounts for about 10% to 20% of the fish's body weight. The daily feeding amount of the adult fish stage gradually decreases to 3%—5%, and the feed coefficient is generally about 35-4.
4. Attach importance to management and regulation of fishpond water quality High-yield large-mouth ponds must have sufficient water sources and good water quality. Fish ponds can store 20-25 meters of water and facilitate irrigation and drainage. The supporting facilities should be equipped with 15 kilowatts of aerator per 3-4 mu. With a pump, pump and other mechanical equipment. In addition to the polyculture of cockroaches, cockroaches, cockroaches and other fish to regulate water quality, but also promote the appropriate use of beneficial microbial agents to automatically adjust the water quality, according to the changes in water color timely replacement of new water, but each change the amount of water is about 10%, not too much. Also insist on opening the aerator regularly, and start the oxygen aerator at the middle of the night (even midnight) before the dawn of low dissolved oxygen to prevent the lack of oxygen in the pond and the floating head of the pond fish. In the afternoon, the upper layer of water is dissolved oxygen at 1-3 o'clock. Should be more than the boot, each boot is not less than 1 hour, increase the lower water dissolved oxygen, reduce the underlying oxygen debt, accelerate the decomposition of the water body material and harmful substances.
5. Large catching, small catching, round catching, and timely listing of large-mouthed black storks The stocking densities are relatively large and prone to size differences. Fishes of commercial specifications should be caught in time to reduce the density and promote the rapid growth of small-sized fish. In general, high-yield, large-mouthed black pupa ponds should be quarantined 4-5 times throughout the year. If the stocking densities are relatively small, some larger-sized black-billed hawksbill species can be properly replenished during the breeding process, especially from November to December each year. It is most suitable when the price is low. Polyculture fish (especially squid) can also be increased in yield by means of round-robin feeding. Through the above measures, it will not only increase the annual production of pond fish, but also provide a balanced market for commercial fish, reduce the risk of breeding, and effectively increase economic efficiency.
Third, adopt new methods to effectively prevent and treat fish diseases. High-yielding large-mouthed black pupa ponds have high stocking densities and feeds are fed in large quantities. If they are improperly managed, they are prone to fish diseases. Once the disease occurs, they spread quickly and cause serious harm. Therefore, in order to deal with fish diseases, we must implement the principle of “preventing the main thing, and preventing the emphasis on governanceâ€. The main measures for preventing fish diseases are: (1) regularly using microbial agents or renewing water; (2) feeding one course of treatment (about 3 days) each half a month with antibacterial drugs plus multidimensional mixed feed; (3) each half Decontaminate with insecticide or sterilizer once a month. (4) Actively collaborate with research institutes to develop new drugs such as Western medicine insecticides (fish and other special killings) and strong oxidizer disinfectants (water purification and disinfection II, SPA disinfection king), etc., without damaging the water quality, with little irritation and no residual poisons. , quick, efficient and safe. After the use of large-mouthed black cockroaches, it rarely occurs.
Largemouth bass common diseases and control methods are as follows:
1, ciliate disease is mainly caused by ciliates, trichoderma, caterpillars and other ciliates parasitizing on the body surface, fins, maggots and other parts of the seedlings, a large number of parasites when the seedlings harmful, serious when the seedlings Wild swim, with a layer of white floccules. Adult fish also occur, but the harm is relatively small. The prevention and treatment method is the use of Chinese herbal insecticides such as compound fish nets, fish and other special effects to kill fish, can increase appetite after use.
2. Bacterial gizzards and gizzards are mainly caused by infections such as columnar bacilli. Diseased fish have white silk and defects, secrete large amounts of mucus, and have difficulty in breathing. Mortality is high. Rotating chlorine dioxide or water purification and disinfection II or SPA disinfection of drugs such as Wang, while feeding with antibacterial drug ingredients, the effect is better.
3. Diseases caused by poor water quality This year, it was discovered that ponds and largemouth bass are more sensitive to quicklime, which can easily lead to large-scale deaths. Therefore, many practitioners rarely use quicklime during the breeding period, resulting in water quality, especially in the later period of culture. Most ponds have a pH value below 7, affecting poor growth of plankton, lack of dissolved oxygen, anaerobic decomposition of organic matter, and increase of harmful substances such as ammonia nitrogen (NH3-N) and nitrous oxide (NO2-N) in water. Oxygen poisoning death.
Prevention methods are as follows:
(1) Lime dumping method: regularly put hydration hydrated lime into piles around the pond, adhere to the principle of a small number of times, usually once every two weeks, each time 5 kg per mu.
(2) Adhere to the open air aerator at 1-3 o'clock in the sunny afternoon for more than one hour, open the morning in the morning on the cloudy day next day, and prolong the boot time in cloudy and rainy days to increase the oxygen in the bottom of the pool.
(3) Regularly use the water quality improver or an appropriate amount of new water.
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