Efficient Culture techniques of Silver Carp

Silver carp is one of the four famous domestic fish, also known as silver carp, etc., is a typical filter-feeding fish, mainly eats zooplankton at the fry stage, and gradually changes to phytoplankton when it is more than 1.5 centimeters long. also eat soybean milk, bean dregs powder, wheat bran and rice bran, more like to eat artificial micro-particle compound feed, let's take a look at the efficient culture technology of silver carp.

Living habits of silver carp

1. Feeding habits: silver carp belongs to pelagic fish, which feeds on plankton all its life. It mainly eats zooplankton in the fry stage, and gradually changes to phytoplankton when it is more than 1.5 cm long, and likes to eat grass carp feces and chicken and cow dung. I am interested in sour food and have an appetite for bad food. Bait has obvious seasonality, in addition to plankton, but also eat a large number of sapropelic bait in Spring and Autumn. The lower the water level in summer, the greater its food intake, and it eats less and moves less in winter.

2. Water temperature: silver carp likes high temperature, and the most suitable water temperature is 2332 ℃. Silver carp have the strongest appetite in hot summer. Lively temperament, like to jump, have the habit of going against the current, but the action is not very agile, more clumsy. Silver carp like fertilizer and water, and individual imitators often gather and swim to the middle and upper layers of the water, especially in the open water area where the water quality is fatter. Timid fear of disturbance, the ability to withstand hypoxia is very poor, hypoxia in the water immediately floating head, some die soon.

3. Reproduction: silver carp has fast growth rate and high yield. The age of sexual maturity of silver carp is 1-2 years earlier than that of grass carp, and the mature individuals are also smaller. Generally, the female fish weighing more than 3 kg can reach maturity, and the relative number of eggs laid by the female fish about 5 kg is about 40-50 000 eggs / kg body weight. Under the condition of pond culture, if there is enough bait, the fish can grow to 500 kilograms in that year, the weight of three-year-old fish can reach 3 kilograms, and the weight of three-year-old fish can reach 30 kilograms in natural rivers.

Culture techniques of silver carp

1. Selection and retention of parent fish: parent fish choose natural species, which requires good health and good gonadal development. The individual weight of silver carp is more than 6 kg, bighead carp more than 10 kg, herring more than 15 kg, grass carp more than 8 kg. The annual renewal rate of parent fish should be about 10%.

2, clean up the fish pond: the parent fish pond should be convenient for irrigation and drainage, silver carp and bighead carp pond bottom should have 20 cm deep silt, green carp and grass carp pond bottom should contain little or no silt. The area is 1 to 5 mu and the water depth is about 1.5 meters. The pond should be cleared before stocking.

3. Matching stocking: the female-to-male ratio of silver carp, bighead carp, green fish and grass parent fish is generally 1: 1: 1.5, and at the same time 810 mandarin fish and 150 tail silver carp are released per mu to control the breeding of wild miscellaneous fish and large zooplankton.

4. Feeding and management: before stocking, the parent ponds of silver carp and bighead carp should put 500,700 kilograms of mature organic fertilizer per mu to cultivate plankton, and proper fertilization should be applied in the future. In addition, soy cake milk should be fed in sunny and warm weather to promote gonadal development.

5. Early induction of labor: female fish can be induced to give birth with dilated abdomen and loose reproductive pores. Generally, female fish are injected with 1000 IU of oxytocin chorionic gonadotropin per kilogram of body weight, or LRH~A40~50 micrograms, and males are reduced by half.

6. Incubation management: the water for hatching should be filtered with a filter to prevent floating objects and wild miscellaneous fish from entering. Before each hatching, the incubator tank and incubator should be cleaned, the appropriate water flow should be provided during the incubation period, and the bottom corner of the water body should be turned frequently to check whether there are accumulated eggs and seedlings to maintain the water quality.

Disease prevention and control of silver carp

1. Gill mildew

[symptoms] the diseased fish do not eat, swim slowly, the Gill is congested and bleed, the Gill flap is a little congested, lose its normal bright red and show pink or pale white, in severe cases, the Gill filament is necrotic, affecting respiratory function, resulting in the death of diseased fish.

[prevention and treatment] ① thoroughly cleans and disinfects the pond to keep the water quality clean and prevent the water quality from deteriorating. It is necessary to apply fermented organic fertilizer to cultivate water quality in ②, not raw application. The pond with ③ should be filled with fresh water quickly to improve the water quality, or transfer the diseased fish to the pond with fresh and clean water quality. Sprinkling ④ 20mg / L quicklime in the whole pool can reduce the content of organic matter in the water and improve the water quality.

2. Printing disease

[symptoms] the diseased fish have approximately round erythema on the body surface behind the dorsal fin, and the scales fall off at the focus, resulting in ulcers and even exposing bones or internal organs.

[prevention and treatment] the faeces of herbivorous animals in ① must be well mixed with quicklime and fermented fully, and then applied after rotten heat to prevent pathogens from entering. When ② fingerling passes through the pond, it can be washed for 5 minutes with 2% salt water for 10 minutes, which can effectively prevent the disease. ③ bacterial toxin clear 0.5ppm or dibromohydantoin 0.3ppm sprinkled all over the pool.

3. Ring disease

[symptoms] when the condition is serious, the Gill filaments of diseased fish are swollen, mucus is increased, and breathing is difficult, which can cause a large number of seedlings to die.

[control] ① 90% crystal trichlorfon 0.3 ~ 0.7ppm sprinkled all over the pool. ② worm sweep is sprinkled in the whole pool at 130ml / mu / m. If the condition is serious, it can be used again every other day.

4. Taeniasis

[symptoms] from the appearance of the diseased silver carp, the abdomen was dilated and locally protruded, the physique was obviously emaciated after ice melting in early spring, the abdominal enlargement was more obvious, the abdominal muscle was very thin, and the sparganum could be drilled out from the pectoral fin.

[prevention and control] ① should close the fry, and kill the first intermediate host, copepod, before going into the pond. ② must persist in cleaning ponds with quicklime in areas with frequent occurrence of tapeworm.