Mesad, commonly known as mud carp, male mud carp and snow mud carp, belongs to the genus mud carp of CYPRINIDAE. Shad is a kind of fish that lives in a warm climate zone, mainly distributed in the south of China. In the Pearl River basin, it is one of the main objects of river fishing and pond culture, and has a breeding history of hundreds of years.
The shad are omnivorous, and they begin to eat zooplankton, such as rotifers, copepods and small cladocera, four days after hatching. After hatching 10 day, the body length was more than 1.4 cm, and besides eating zooplankton, it began to eat phytoplankton. After that, more and more phytoplankton were eaten, until about 40 days after hatching, when the body length was more than 4 cm, phytoplankton was mainly eaten. At the same time, Shade likes to lick and scrape algae that grow on the surface of underwater soil or rocks. In addition, a small amount of zooplankton and organic debris were swallowed. In the case of pond culture, you can eat rice bran, peanut bran and other feeds.
The shad is a warm-water fish with a strong appetite at the temperature of 15℃ to 30℃. When the water temperature is higher than 3 1℃, the appetite decreases. When the water temperature is lower than 14℃, it will gather in the deep water area with less activity. Stop eating when the water temperature is lower than 13℃. When it is below 7℃, it cannot survive. Because of the poor cold resistance of shad, shad are usually placed in a deep pool sheltered from the wind and sun when wintering in the Pearl River Delta pond, and sometimes additional cold protection measures are needed.
As a bottom fish, shad has low requirements for dissolved oxygen and can adapt to more fertile water. When the water temperature is between 20℃ and 28℃, the dissolved oxygen is lower than 1 mg/L, and people can still eat normally. When the dissolved oxygen is as low as 0.24 mg/L, there is no asphyxiation. Therefore, it can be stocked in high density, generally about 0/000 tail per mu/kloc.
The growth rate of shad is slower than that of other domestic fish, especially in ponds with high stocking density. 1 year-old fish weighs about 70g, 2-year-old fish weighs about 250g, 3-year-old fish weighs about 350g and 4-year-old fish weighs about 500g.
However, the yield of shad population is high and the edible specifications are not very high. You can go on the market with a weight of about 200 grams, and the economic benefit of stocking shad is still relatively high. The fry propagated in summer were cultivated into fry and fish ponds in two stages in the same year, and the weight of fry and fish ponds was 5-100g. At the end of the year or the following year, they were put into fish ponds for interplanting to cultivate medium-sized fry with the weight of 50-100g. In the third year, they were put into fish ponds for mixed culture, and the commercial specifications of 200g were cultivated. The second anniversary fish is listed in summer; It went on the market in autumn. After three autumns, it was called "Sanqiu Kun" and generally weighed about 250g.
Shad has become an essential variety for pond culture because of its wide feed sources, adaptability to fertile water environment, strong disease resistance and high population yield.
Siniperca chuatsi has a slender figure, soft fins and rapid growth, which is a suitable feed for Siniperca chuatsi. By improving the recovery index of shad, the yield of pond is obviously affected.
Breeding techniques and methods:
I. Pond conditions
The suitable pond area is 5-8 mu, the water depth is 1.2- 1.5 m, and the sludge in the pond is 20 cm. The water quality is fresh and pollution-free, which is convenient for water injection and drainage.
Second, clean the pond and disinfect it
Three days before stocking fry, do a good job in drying ponds and ponds, and then clean the ponds with 2.5 kilograms of bleaching powder.
Third, water quality management.
After 5-7 days, the fry are mainly fresh water, and fat water cannot be used. After 5-7 days, the water level should be controlled at 0.6-0.8m, and appropriate fertilization can be carried out. Generally, chicken manure particles are 5-7.5 kg/mu and evenly put into the whole pond. The transparency of the pond water should be controlled at about 30cm, the normal pond should be added with water once every 7- 10 days, and the water level should be controlled at 65438+.
Fourth, summer flowers are divided into ponds.
1. The shad fry bloom in summer, from early June to late July, with a specification of 0.3 cm and a yield of 300,000-600,000 per mu. It takes 15-20 days to cultivate the pond and the survival rate is 60-65%. Then, according to the breeding conditions and the food intake of Siniperca chuatsi, they are raised separately in a planned way.
Fifth, fry are kept in separate ponds.
The culture time can be divided into three sections from the end of 6 friends to the beginning of 10. At present, according to the aquaculture production situation in our city, the first stage of pond production is mainly carried out from late June to early August (generally, one-time aquaculture is the main one according to the market supply and demand situation in our city). The stocking specification is 5,000-7,000 fish per kilogram, with a yield of 40,000-50,000 fish per mu. The specification for coming out of the pond is 0/20-/0/50 fish per kilogram, with a yield of 300-320 fish per mu. In the second stage, the stocking specification is 10 from early September to early October, and the stocking specification is 1000- 1200 pieces per kilogram, with 50-60 pieces per acre 10000. Reasonable arrangement of mixed stubble in each period can reach 500-600 kg per mu.
Six, feeding management
After the fry enter the pond, the stage of entering the pond is mainly soybean milk, supplemented by vegetable cakes, and fed twice at the time of splashing. After the fry are cultivated for a week, they should be "sown" at the bottom of the pond, and the feed should be sufficient to make the fry grow healthily. Generally, 0.5 soybeans are needed per 10000 seedlings. After the pond is divided, the fry should use organic fertilizer according to the fat of the bottom material. Generally, per mu 100- 150 kg is used to cultivate red worms as opening material, and then they are fed with vegetable cakes. General production 1 kg shad needs 1.5 kg vegetable cake.
VII. Disease Prevention and Control
Put the fry in the pond for about a week, mainly to prevent the occurrence of "bubble disease". Therefore, clean water should be put in the pond and added regularly. The prevention and control of rotifers and trypanosoma should be focused on during the breeding period. 1 mu of water depth 1 m, spray 0.5mm baichongjing on the whole pond, and then spray 0.2kg of fish frog rotten skin hemostatic on the whole pond the next day to make shad grow healthily.
Iodophobia of shad
Iodine-borne disease of shad is a fish disease caused by wild carp and Foshan parasitism. There are two bottle-shaped polar sacs in the front end of the shell of Iododinium in Foshan. The polar filament is spiral, and there are two embryo nuclei and an obvious iodophor and spore in the cytoplasm.
It's oval. However, the spores of wild carp iodophor are oval. A small number of milky white tumor-like cysts appeared on the surface of shad species invaded by iodine bubbles, which made the fish thin and unable to swim until death. There are often many punctate cysts on the body surface of wintering shad, which will not kill the fingerling, but will affect its growth and development. The disease is mainly prevalent in Guangdong and Guangxi.
A large number of iodophor spores can be produced by removing the body surface cysts and pressing them into thin slices under the microscope.
Prevention and control methods:
1. Thoroughly cleaning the pond with quicklime can inhibit spore reproduction and reduce the occurrence of this disease;
2. Before stocking the fingerlings, put 500g of potassium permanganate into 1 m3 water, stir to fully dissolve it into 500mg/l solution, soak the fingerlings for 30min, or put 50g of lime nitrogen into 1 m3 water, fully stir to form a suspension, and soak the fingerlings for 30min.