Methods and skills of shrimp culture in ponds.

High-yield culture method of freshwater shrimp in pond

In order to change the current situation of low yield of freshwater shrimp cultured in ponds, technical measures such as raising shrimp twice a year and feeding complete pellet feed can achieve good economic benefits. The main technical points are as follows.

1. Pond requirements. Macrobrachium nipponense has high oxygen consumption and is not tolerant to hypoxia. At the same time, Macrobrachium nipponense is a benthic animal with poor swimming ability and likes to move at the bottom of the pool. Therefore, the pond area for cultivating green shrimp should not be too large. Generally, the pond area for cultivating shrimp is 3-8 mu, the slope ratio 1: 3- 1: 3.5, the water depth 1.5 m or so, and there is no silt at the bottom of the pond and no pollution in the water source, which meets the national fishery water standard. The ponds were thoroughly cleaned and disinfected with quicklime half a month before the seedlings were released, and aerobic facilities were installed in each pond.

2. Plant aquatic plants. Shrimp is a crustacean, which has the phenomenon of shelling and cannibalism. Therefore, in order to avoid cannibalism, it is necessary to plant some suitable aquatic plants to prevent shrimp from cannibalism. There are mainly two kinds of aquatic plants planted: one is water peanuts planted around the shallow water near the pool; The other is submerged plants planted at the bottom of shallow ponds, such as Kuroshio and Elodea. These aquatic plants reproduce quickly, so when there are too many aquatic plants in the pond, they can be fished out manually, so that the aquatic plants in the pond are best distributed in a star shape. Generally speaking, the growth area of aquatic plants should be controlled at about 30% of the total surface area of the pond.

3. Set the grid. Set 10 ~ 33 mesh knotless summer flower net in the middle of the shrimp pond and fix it with bamboo frame. According to the shape of the roof truss, it is set 20 ~ 40 cm below the water surface, and the slope is 15 ~ 20 degrees, so that the green shrimp can crawl up and down. Each row of nets is 3 ~ 4 meters wide, depending on the pond. Generally, two rows of nets can be set up in a pond of about 5 mu.

4. Fried stockings. The growth rate of freshwater shrimp is fast and the culture cycle is short. Under the suitable culture environment and sufficient bait conditions, after two months of culture, each shrimp fry can reach the commodity specification of more than 3 grams. Therefore, the breeding mode of stocking twice in spring and summer and raising two crops a year can be adopted.

Stocking will be carried out in summer around July, with 40,000 to 60,000 shrimps per mu about 1cm and10-20 days later, a small amount of silver carp will be released. When stocking, the specifications should be neat and healthy, and the stocking time should be chosen in the early hours of sunny days or when cloudy days are not boring. Avoid the peak period of seed hulling when stocking. From August to September, a batch of young shrimps will lay eggs and hatch. By the end of the year, these shrimps can generally grow to 2 ~ 3 cm, which can be used as spring stocking seedlings, with 30 ~ 50 thousand per mu.

5. Feeding management. According to the feeding habits of freshwater shrimp, adhere to the principle of four fixed feeding. Generally, feed twice a day, 8:00-9:00 in the morning and 5:00-7:00 in the afternoon, accounting for 1/3 of the total in the morning and 2/3 in the afternoon. Bait should be thrown in shallow water with aquatic plants and evenly. Generally, the daily feeding amount of young shrimps is controlled at 3% ~ 5%, and the fine pellet feed is mainly used in the early stage. With the growth of the individual, you can feed the granular feed with corresponding specifications appropriately. When feeding, we should carefully observe the feeding situation of freshwater shrimp, and generally it is advisable to eat it within 2 ~ 4 hours at a time.

6. Water quality management. In hot season, water must be added or changed 1 time every week, and the old water at the bottom should be drained first, and then fresh water with a depth of 15 ~ 20cm should be replenished. When the floating head of freshwater shrimp is found at night or early in the morning, the aerator must be turned on to replenish fresh water, especially in the weather before sultry or thunderstorm, and measures should be taken to replenish water and change water 24 hours a day to keep the pool water in a state of micro-flowing water.

7. Daily management. Disinfect the water with quicklime water or disinfectants such as dibromohydantoin and chlorine dioxide every half month to kill germs and pathogens. At the same time, to observe whether the blue shrimp is attached with ciliates, the whole pool can be sprayed with copper sulfate aqueous solution, and the application concentration of the whole pool is 0.7ppm, and it can be reused every 7 days 1 time.

8. timely arrest. Shrimp can be caught and marketed when it grows to 4 ~ 5 cm. Generally, the seedlings released in spring will be caught in May-July and released in summer in September-165438+1October.

Treatment of turbid water in shrimp ponds in rainy season

Every April and May, the peak season of shrimp culture in South China begins to arrive. In this season, the northeast monsoon turns into the sub-south monsoon season, the temperature changes greatly, and the rainfall increases, which often changes the water color of the shrimp pond where prawns are being cultured from brown green to turbid milky white. The main reasons for this situation are sudden change of weather, death of phytoplankton, lack of oxygen, or explosive reproduction of zooplankton, which eats a lot of algae. If the transparency of the pond is high and the number of phytoplankton cannot meet the needs of zooplankton, the phytoplankton will be eaten up, thus losing its original water color and becoming turbid. Because the color and transparency of the water in the pond are determined by the species and quantity of phytoplankton in the pond.

The danger of muddy water lies in the lack of oxygen in the pond. Because the main source of oxygen in the pond is photosynthesis of phytoplankton. It is reported that the oxygen content produced by phytoplankton photosynthesis accounts for 965,438+0.3%-65,438+0.000% of the dissolved oxygen income in seawater ponds, while the diffusion of the atmosphere only accounts for 5.3%-7.8% of the dissolved oxygen income in seawater ponds. The turbid water in the pond means that there are few phytoplankton in the pond, and of course there is little photosynthesis, so the oxygen produced naturally decreases.

It is precisely because June and July are rainy days, heavy rains and heavy rains. In this weather, sunshine is weakened, photosynthesis is reduced, and oxygen supply is also reduced. In this bad weather, if the daily management work is not effective, prawns are easy to get sick. Shrimp farmers who lack scientific knowledge are at a loss in the face of this water color. In fact, it is not difficult to understand its outbreak principle and solve the problem of turbid water.

Turbid water will not only affect the breathing and growth of prawns due to reduced oxygen supply, but also lead to the deterioration of water quality. Because there are a lot of prawn excrement, residual bait and biological carcasses at the bottom of the pond, if these substances are rich in oxygen, they are prone to oxidation reaction, and harmful substances such as ammonia nitrogen, nitrite and hydrogen sulfide are less and less. Under anoxic conditions, the reduction reaction of pond sediments increases, producing more and more harmful substances, leading to shrimp stress and diseases.

Turbid water can be treated as follows:

Kill some zooplankton with disinfectant. Commonly used quicklime, the concentration is 20ppm (20g per cubic meter of water, if the water depth is 1 m, the quicklime per mu is about13kg). First, dissolve quicklime in water, dilute it with water, and spread it evenly in the whole pool. After using quicklime, water will become clearer. Other disinfectants can also be used, but the concentration must be based on the safety of prawns.

Stop feeding 1-2 meals. The purpose is to make shrimp hungry, grab some zooplankton, reduce the number of zooplankton and facilitate the cultivation of algae.

Change the water by 5- 10 cm. The purpose of changing water is to replenish algae species. Because there are few algae in turbid water, it is more difficult to cultivate algae with few algae species, so it is necessary to increase the content of algae species to facilitate the fertilization of water, so as to cultivate algae in a short time. If you are raising shrimp or fish next to your pond, the water color is good and there are no other diseases, you can row some to supplement algae, and the effect is also very good.

Fertilize immediately. The fertilizer used should be inorganic fertilizer, not organic fertilizer. According to many shrimp farmers in recent years, using organic fertilizer to fertilize water makes shrimp more likely to get sick. According to a shrimp farmer in Beihai, Guangxi, in the first half of 2004, 80% of shrimp ponds used chicken manure to fertilize water. Shrimp farmers in Doumen, Guangdong have the same reaction. Because chicken manure is an organic matter, it is not easy to dissolve in water and is not easy to be absorbed and utilized by unicellular algae. After it is deposited at the bottom of the pool, it is easy to rot and stink, polluting the bottom of the pool. The deterioration of water quality is often caused by the deterioration of sediments. At the same time, if chicken manure is not handled properly, it will carry bacteria and viruses, which will easily cause diseases of prawns.

Use unicellular algae auxin. It is prepared according to the special nutritional requirements of unicellular algae and contains high-activity nutrients such as nitrogen, phosphorus, potassium and silicon. It is beneficial to the reproduction of unicellular algae and has a long validity period. Generally, only one-time fertilization is needed to raise shrimp. The dosage is also small. Generally, the water depth is 1 m, and it is enough to put 1- 1.5 kg per mu. The price is also cheap, generally 6-8 yuan per mu. It is relatively simple to use, just add water to dissolve, dilute and sprinkle all over the swimming pool. The effect is also quick, the water color will turn brown-green within 24 hours, and the expected effect will be achieved within 48 hours.

Fertilization and watering should be done on sunny days in the morning, not on cloudy days and rainy days.

Combined use of microbial agents, such as Bacillus, photosynthetic bacteria and EM bacteria.

In addition, the application of some zeolite powder and the rational use of aerator have good results.

In a word, turbid water is extremely harmful to the prawns being cultured. When it first appeared, prawns had no obvious abnormal symptoms, but if it was not treated in time, the consequences would be unimaginable. It is necessary to find and treat in time, change the color and transparency of water in time, maintain the ecological balance of aquaculture water, and prevent the occurrence of shrimp diseases.

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