Because on the one hand, aquatic plants can supplement plant feed for crayfish, on the other hand, aquatic plants can also purify the water quality of ponds, and the survival rate and quality of shrimps are also high in ponds with good aquatic plants. However, the area of aquatic plants should not exceed 60% of the total area of the pond, and snails must be raised in the pond before and after Qingming every year. Whether to supplement some snails in the future can be decided according to the specific situation of the pond.
2. Crayfish culture, which can be cultured in ponds, has the following points:
(1) After the cleaning and disinfection of the pond is finished, drain the pond water, dig out excess sludge, and keep the sludge at about 10 cm. Freeze-dry the pond all winter until the surface turns white to accelerate the elegance of organic matter. After spring, 80 ~ 100 cm water was injected into the pond, and quicklime and tea seed cake were mixed for disinfection, with the dosage of 50 kg/mu and 25 kg/mu respectively, in order to kill harmful organisms such as germs and parasites.
(2) Create an ecological environment. After the effect of pond cleaning disappears, the fermented and disinfected livestock manure is applied to the pond at the dosage of 150 ~ 200kg/ mu to cultivate plankton and provide sufficient biological bait for crayfish fry entering the pond in the future. After fertilization, compound aquatic plants such as Elodea nuttallii, Kuroshio, Zizania latifolia, Phragmites australis, Alternanthera philoxeroides and duckweed are transplanted into the pond, so that the coverage rate of aquatic plants accounts for 50% ~ 60% of the total culture area, providing plant bait for crayfish.
(3) The stocking specification of fry is 2 ~ 3cm, the density is 6000 ~ 8000 fish per mu, and the time is from March to April. Choose sunny morning and evening to raise shrimp seedlings, and the specifications of shrimp seedlings stocked in the same pond and batch should be consistent. In order to make full use of water space and bait resources and improve the productivity of the pond, the stocking specification can be 0/00 gram of silver carp and bighead carp per mu/kloc. Before stocking, the seedlings should be soaked in 3% ~ 4% salt solution for 5 ~ 10 minutes to kill bacteria and parasites on the body surface.
(4) Water quality adjustment: add 1 time every 7 ~ 10 days, and add 20 cm fresh water each time to keep the pool water fresh; Change water every 20 ~ 30 days 1 time, and change 20% ~ 30% old water every time, and keep the transparency at about 30 cm; Use 1 time of quicklime every 10 ~ 15 days, the dosage is 10 ~ 15 kg/mu, and the PH value is maintained at 7.5 ~ 8.5;
Use 1 time every 20 days or so (main components: lactic acid bacteria, Bacillus, streptococcus faecalis, EDTA, water purifier), and the dosage is 200ml/L, so as to improve the water quality of the old consistency (blue-green, black-red, rust color, etc.). ), increase transparency, improve water quality, quickly absorb and degrade toxic and harmful substances such as hydrogen sulfide, ammonia nitrogen and nitrite at the bottom of the pond, and improve the bottom material. Open the micropores in time to increase oxygen, and keep the dissolved oxygen above 5 mg _ L.
(5) During the cultivation stage, young shrimps are mainly fed with compound feed with crude protein content of 36% ~ 40%, and the daily feeding amount is 3% ~ 5% of the total weight of shrimp in the pond. In addition, some fresh small miscellaneous fish should be properly fed to meet the nutritional needs of the development and growth of young shrimp; In the adult shrimp culture stage, the compound feed with crude protein content of 30% ~ 35% is mainly fed, and the daily feeding amount is 4% ~ 5% of the total weight of shrimp in the pond.
In addition, half-cooked corn, soaked and germinated wheat and fresh small miscellaneous fish are properly fed to improve the specifications of adult shrimp and increase the aquaculture yield. In the whole process of crayfish culture, feeding is twice a day, and feeding is 1 time before sunrise in the morning and after sunset in the evening, mainly in the evening, accounting for 60% ~ 70% of daily feeding.
Put the bait on the shore or shoal, and let crayfish develop the habit of feeding at fixed points. The specific feeding amount should be controlled scientifically according to the season, weather, water quality, water temperature, crayfish molting and feeding. Generally, it is advisable to eat it basically 2 hours after feeding.
(6) During the molting period, special attention should be paid to the following two points in managing the molting period of crayfish:
① Maintain good water quality. Fresh water should be added before molting to keep the water fresh, so that crayfish can molt in a good water environment to shorten the molting time and accelerate their growth.
2 is to ensure nutrition. Crawfish grow up with molting again and again. Every time it molts 1 time, its body size will increase a little and its food intake will also increase. In addition to increasing the content of protein in feed, some snails, mussels, small miscellaneous fish, etc. It should be added to increase nutrient supply and promote crayfish molting and hardening of shrimps after molting.
(7) The prevention and control of shrimp diseases should adhere to the principle of "prevention before illness, early treatment after illness, prevention first, and combination of prevention and control". Through strict pond cleaning and disinfection, putting high-quality shrimp seedlings, creating a good ecological environment, feeding high-quality feed, feeding drug bait regularly and other preventive measures, shrimp diseases can be effectively prevented.
Once crayfish get sick, it is necessary to diagnose the cause in time, and treat the disease with drugs with high efficiency, low toxicity, low price and little side effects allowed by the state as soon as possible to control the spread of shrimp disease.
Extended data:
1. Crayfish has a high content of protein, soft meat and easy digestion, which is an excellent food for people who are weak and need to be nursed back to health after illness; Shrimp meat is also rich in magnesium, zinc, iodine and selenium. Magnesium plays an important role in regulating heart activity and protecting cardiovascular system. It can reduce the cholesterol content in blood, prevent arteriosclerosis, dilate coronary artery, and help prevent hypertension and myocardial infarction.
2. Crayfish contains astaxanthin, which is a strong antioxidant. Scientists at Osaka University in Japan have found that astaxanthin helps to eliminate the "jet lag" caused by jet lag. In addition, crayfish can also be used as medicine, which can eliminate phlegm and relieve cough and promote postoperative wound healing.
References:
Five problems that should be paid attention to in the culture of China crayfish? Baidu Encyclopedia _ Crayfish? Key points of pond culture technology of crayfish in China