I. Ecological habits 1, diet Cichlid is a carnivorous fish, which mainly feeds on zooplankton during the fry and fingerling stages. When the body length is about 15cm, the food habit is changed, and small screws are eaten. With the development of hypopharyngeal teeth, the crushing function is enhanced. Juveniles are mainly mollusks, such as cockroaches and snails. In addition, shrimp, crabs and insect larvae are also eaten. 2, growing The herring is large in size and grows quickly. The maximum weight is up to 70kg. One-year-old fish can grow to 500g, 2nd-instar fish to 2.53kg, and 3rd-instar fish can reach 6.57.5kg in good conditions. The body length of herring is the fastest in 12th instar, and its body length grows slowly after 5th instar; body weight gain is the fastest in 34th age and continues to increase afterwards. 3, reproduction Herring is a migratory fish. It grows and develops in waters attached to rivers. It enters winter through rivers in winter, and it goes up after winter. The gonads develop rapidly and mature in the process of upstream. They reproduce in spawning grounds of rivers and broodstocks after spawning. Also entered the subsidiary water body fattening. Every year in the breeding season of 56 months, the water temperature is required to be 1828°C. When the spawning ground rises, the water flow rate is 12m/s, and the flow becomes chaotic. The broodstock begins to spawn. Greenfish eggs float, and develop with water flow. The sexual maturity of herring is: female 57 years old, male 45 years old. Spawning type: Sexually mature individual gonads mature once a year and spawn once. The herd size of the herring increased significantly with body weight. Generally, 1520kg of broodstock had a fecundity of about 600,000 grains. Second, artificial breeding 1, broodstock source The natural seedlings in the river basin or the seed stocks produced by the state's original seed farm, or the herring adults collected from natural resource pools, or natural waters that have not been artificially stocked, such as rivers, reservoirs, lakes, etc., are cultivated as Broodstock. Inbreeding offspring cannot be used as a source of broodstock... 2, broodstock breeding (1) The broodstock requires more than 6 instars and weighs more than 15 kg. It is stocked at a ratio of 1:1.5 for males and females, and has about 10 tails of herring for 15-20 kg. (2) The brooding pond is flat at the bottom of the pool. Sandy loam soil is better, water quality is kept fresh, and snails, clams, and oysters are mainly fed. Small amount of bean cakes and malt are added, and new water and flush water are regularly added. Generally, the winter months Flush once and keep the water depth more than 2 meters. After the spring, lower the water level to increase the pool water temperature. Flush the water once a week. In the middle of April, increase the number of flushes. Rinse the water 2 to 3 days to promote gonad maturation. (3) In the broodstock pond, a small amount of whitefish can be used to regulate the water quality. At the same time, carnivorous fish such as blackfish and California quail can be properly reared to catch the wild fish in the pond, which will facilitate the broodstock breeding and increase the efficiency of the pond. 3, brooding fish production (1) Production time, water temperature: In the middle and lower reaches of the Yangtze River, urine production time is mid-to-late May. The urine production water temperature is 25~28 main and the most suitable. (2) Broodstock sorting: The maturity of the broodstock directly influences the oxytocin production effect. The identification criteria is that the male fish has a semen out of the abdomen by pressing lightly. It immediately spreads out after encountering water. The abdomen of the female fish is enlarged, soft and elastic, and the abdominal scales are sparse. In order to improve the maturity of the population, the network can be checked in mid-April. For poor maturity, according to individual size and maturity, according to individual size and maturity, LRH-A3 ~ 5 micrograms/tail were injected. (3) Injecting oxytocic agents: commonly used oxytocins are LRH-A, DOM, PG, etc. Usually two kinds of mixed use effect is better. My field uses three-needle injection, and the rate of coercion is high, as high as 95%. LRH-A 1 microgram per kilogram of broodstock at the end of the first shot, needle distance 20 hours; LRH-A 5 micrograms per kilogram of broodstock at the end of the second shot, needle distance 8 hours; LTH-A 20 micrograms per kilogram of the third needle female fish injected Plus PG3 ~ 4 mg or add DOM4 ~ 5 mg, the dose of male and female fish as the case of injection of female parent fish dose of 1/3 ~ 1/2, injections are used intrapleural injection. 4, heat and artificial insemination The length of the effect varies with the temperature of the water. It has been observed that when the water temperature is 26 to 28 degrees, the effect time is 6 to 7 hours. Bring broodstock to the scheduled time and combine actual estrus conditions to capture the broodstock for artificial insemination. When inseminating, pay attention to light and rapid movement. When mixing eggs and sperm, add 0.6% normal saline, extend insemination time, and insemination. Avoid direct sunlight and splashing of rain, increase the fertilization rate, and the normal fertilization rate is over 90%. 5. Incubation After the water-absorbed fertilized eggs are hatched in a hatchery ring or hatching tank, the flow rate of water is such that the fertilized eggs can be washed and rolled, and the hatching water should be separated into rows, and it should not be recycled. After the fish fry come out of the membrane, the water flow should be appropriately increased to prevent the seedlings from sinking and suffocating. After 24 hours of hatching, the water flow should be appropriately reduced to avoid excessive water consumption and the consumption of fish seedlings. In the same development period, the flow rate of water is less than the nighttime in the daytime. If the weather is abnormal and the temperature difference is large, it should be appropriately reduced to avoid excessive consumption of fish seedlings. The flow rate of water in the same development period is less than that during the day. If the weather is abnormal, the water flow should be increased when the temperature difference is large.
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