Habit:
Grass carp grass carp generally prefer to live in the middle and lower layers of rivers, lakes and other waters and near-shore areas with many aquatic plants. Mature individuals, which has the migration habit of rivers and lakes, lays eggs in rivers and flowing water. After laying eggs, the parent fish and juvenile fish enter tributaries and Tongjiang lakes, and usually feed and fatten in submerged shoals and flooded areas and water bodies attached to main tributaries (lakes, rivers, harbors and other water-covered areas). In winter, it overwinters in the deep water of the main stream or lake. Grass carp is a typical herbivorous fish with lively temperament, fast swimming, frequent foraging in groups and gluttony. It feeds on zooplankton in the fry stage, insects, earthworms, algae and duckweeds in the juvenile stage, and completely feeds on aquatic higher plants, especially Gramineae plants, when the body length is about 10 cm or more. The species of plants eaten by grass carp vary with the food base in the living environment.
breed
Grass carp (pomfret) The reproductive situation of grass carp is similar to that of other domestic fish, and it cannot lay eggs in still water under natural conditions. Generally speaking, the suitable spawning sites are the confluence of the main stream of the river, the deep channel waters on one side of the meander, and the sudden contraction of the two sides of the river. The reproductive season is similar to that of silver carp and a little earlier than that of herring and bighead carp. The reproductive period is from April to July, and it is concentrated in May. Generally, when the river rises early and violently, and the water temperature can be stabilized at around 18℃, grass carp spawn on a large scale. The reproductive habits of grass carp are similar to those of other domestic fish. The ovaries of grass carp reach maturity and overwinter in the third developmental stage throughout the winter (1February to February). In March and April, when the water temperature rises to about 15℃, the stage Ⅲ oocytes in the ovary quickly develop to stage Ⅳ, and begin reproductive migration, and complete the development from stage Ⅳ to stage Ⅴ in the process of upstream migration. When it encounters hydrological conditions suitable for spawning, it will spawn immediately. Usually spawning is carried out in the water layer, and the fish body does not float above the water surface, which is commonly called "suffocation"; However, when encountering good reproductive ecological conditions, such as the sudden rise of water level accompanied by thunderstorm, the female and male fish chase in the upper layer of the water and appear the phenomenon of "floating row" with trembling back and abdomen. After fertilization, due to the water absorption and swelling of the egg membrane, the diameter of the egg can reach 5 mm, and it floats with the water, and develops best at about 20℃, and the fry hatch in about 30-40 hours.
grow
Grass carp grows rapidly. As far as the whole growth process is concerned, the fastest growth period of body length is 1-2 years old, and the fastest growth of body weight is 2-3 years old. When the 4th instar fish reached sexual maturity, the growth slowed down significantly. 1 winter fish is about 340mm long and 750g heavy; The winter fish is about 600 mm long and weighs 3.5 kg. The body length of the 3-year-old fish is about 680 mm and its weight is about 5 kg. The length of winter fish is about 740 mm and the weight is about 7 kg. 5 winter fish can reach about 780 mm and weigh about 7.5 kg; The largest individual can reach about 35 kg. Grass carp grows fast and has a large individual, and the largest individual can reach 35 kg. The meat is tender and delicious. Every 100g of edible part contains protein15.5-26.6g, fat1.4-8.9g, heat 83-187kcal, calcium18-160mg and phosphorus 30-3/60mg. Grass carp (Ctenopharyngodon idellus) is often regarded as the main stocking object for pond culture and lakes, reservoirs and rivers because of its simple feeding habits, wide sources of bait, rapid growth and high yield. Since 1958, artificial spawning, fertilization and hatching techniques have been successful, and fry and fingerlings have become the main intensive breeding objects in China. Grass carp is also used by fishermen to wander outside for one or two years to clear grass in the water and along the coast, so as to open up wasteland and weed. Grass carp is called "pioneer" because it can quickly remove all kinds of grass in water. At the end of the Tang Dynasty, there was a record in Guangdong that the barren fields were ridged, irrigated with rainwater and stocked with grass carp for one or two years to eliminate weeds and make the fields mature. Grass carp is often mixed with silver carp and bighead carp, which are fed with grass, while the feed left in the water and the waste discharged by grass carp are used to cultivate plankton as feed for silver carp and bighead carp.
Breeding technology
Efficient and rapid culture technology of pollution-free grass carp In the past, the conventional culture of grass carp was mainly polyculture, which took three years to develop, with high cost and long capital occupation. The author summarized and popularized the high yield, high efficiency and rapid culture technology of pollution-free grass carp, which is introduced as follows. 1, pond requirements: the pond area should be 10-20 mu, the water depth should be 2-2.5 meters, and the silt thickness should not exceed 20 cm. Each 10 mu pond is equipped with an aerator and an automatic bait feeder with a power of 3kW each 1 set. 2. Pond cleaning: Drain the pond water in winter and freeze for more than 20 days. Before stocking the fingerlings 15 days, feed water10-20cm, and clean the pond with quicklime150kg per mu for disinfection. 3. Fish stocking: Before and after the Spring Festival, 300 grass carp species with the specification of 200-250g/fish, 300 crucian carp species with the specification of 15-20/kg, 50 silver carp species with the specification of 5-6/kg and bighead carp species with the specification of 10. Soak and disinfect the fingerlings with 5% salt solution for 5- 10 minutes before stocking. 4. Feed feeding: mainly feed pellet feed with protein content of 28-32%, supplemented by turquoise feed. Feed feeding follows the principles of "coarse before fine" and "four decisions and four observations". Generally, it is fed twice a day, and it is appropriate to eat it within 2 hours and grass carp is 80% full. From March to June, the content of protein fed is