1. Pond requirements and preparation before releasing seedlings

Currently, Japanese prawns can be cultured in general shrimp ponds. Considering that Japanese prawns have the habit of burrowing in sand, sand should be selected for the breeding pond. Quality or sandy muddy soil is better, followed by muddy soil. After a period of cultivation and production in a shrimp pond, some silt and organic debris will be deposited on the bottom of the pond. If it is not cleaned up, it will gradually deteriorate the benthic environment of the shrimp pond, causing the shrimp to grow slowly, even get sick and die, and reduce the survival rate of the culture. Therefore, about one month before the water enters every year, the shrimp pond must be desilted and disinfected, the embankment must be solidified, and the bottom of the pond must be fully dried. Quick lime, bleaching powder, etc. can be used for pond disinfection. The dosage of quicklime is 50 to 100 kilograms per mu, which can not only disinfect but also increase the pH value of the soil. Bleaching powder has a strong killing effect on protozoa and bacteria. When using it, put a small amount of water in the shrimp pond before entering the water. The dosage is 3×10-5~5×10-5 and sprinkle with mixed water. Use tea seed cake to remove harmful fish, the dosage is generally 1.5×10-5~2×10-5.

Introduce water to fertilize and cultivate basic bait. Generally, 10 to 15 days before the seedlings are released, the shrimp pond is filled with about 80 cm of water. Fertilization is carried out on sunny days. Apply 2 to 3 kilograms of urea per acre. After that, top dressing will be carried out every week depending on the fertility of the pond water. In shrimp ponds with good natural basic feed, if the shrimp body length is less than 3 cm in the early stage of breeding, it is basically not necessary to add feed.

2. Shrimp seedlings stocking

(1) Selection and transportation of shrimp seedlings. Japanese shrimp cultured seedlings should be selected with a total length of more than 0.8 cm, small individual differences, clean body surface without parasites, strong and lively, and strong jumping ability. At the same time, we should carefully understand and observe the water quality of the breeding pool, the bait used, the source and condition of the broodstock.

It is better to use non-toxic plastic film bags for the shipment of shrimp seedlings. A film bag with a capacity of 30 liters can hold 15,000 seedlings in about 5 hours of transportation when the water temperature is 20°C. ; In about 10 hours, 12,000 seedlings can be loaded; in about 15 hours, 8,000 seedlings can be loaded, preferably no more than 20 hours.

(2) Conditions for releasing seedlings.

① Pool water depth: about 1 meter, not too shallow. The water color is yellow-green, fat and refreshing.

②Water temperature: The water temperature of the shrimp pond is preferably above 18℃ when releasing seedlings. Growth will slow down when the temperature is low, and the water temperature difference between the breeding pond and the nursery pond should not exceed 2℃.

③PH value: The pH value of the shrimp pond should be between 7.7 and 8.8, and the minimum should not be lower than 7.5.

④ Salinity: The salinity of the shrimp pond should be between 10‰ and 30‰, and the difference between the salinity of the shrimp pond and the nursery pond should not exceed 5‰.

(3) Seedling density. The density of shrimp stocking is not static. It should be comprehensively considered based on the shrimp pond conditions, natural conditions, economic conditions, technical conditions and other practical conditions, and the number of stockings should be determined according to local conditions and time. In general, ponds with good conditions can stock around 15,000 seedlings per acre, and can also be cultured in double or multiple crops. The first release of seedlings is 6,000 to 8,000 per mu, and the second release of seedlings will be carried out after capture in mid-July to make full use of the pond water body and improve economic benefits. Note that the seedlings should be released at the downwind end of the shrimp pond to avoid headwinds blowing the shrimp seedlings to the edge of the dam; try to avoid muddying the pond water when releasing seedlings.

3. Feeding

(1) Determination of daily feeding amount. In the early stage of breeding, a small hanging net can be used, and in the middle and later stages, a rotary net quantitative method can be used to measure the total weight of shrimp in the pond, and then determine the amount of feed. Under normal circumstances, when the shrimp weight is 1 to 5 grams, the daily feeding amount is 7% to 10% of the total shrimp weight; when the shrimp weight is 5 to 10 grams, the daily feeding amount is 4% to 7%; when the shrimp weight is 10 to 20 grams, the daily feeding amount is Feed at 3% to 4% (all refer to the dry weight of artificial compound feed).

(2) Feeding time and quantity. Japanese prawns lurk at the bottom of the pond with little activity during the day, come out to feed after sunset, and gradually return to lurking in the sand after a full meal at midnight. According to this habit, feed feeding should be carried out after sunset and end at midnight. Among them, the peak feeding period of Japanese shrimp is more than an hour after sunset. At this time, 50% of the daily food amount can be fed, 35% of the daily feed can be fed after 3 hours, and 15% at midnight. Adjustments will be made based on the amount of Japanese shrimp feeding.

4. Water quality control

(1) Water temperature. Penaeus japonicus grows quickly when the water temperature is 18 to 28°C. When the water temperature exceeds 28°C, the shrimp is prone to disease and death. When the water temperature is lower than 18°C, the shrimp grows slowly and the food intake is reduced below 13°C.

In order to maintain a suitable water temperature during the Japanese shrimp farming process, the breeding production time must first be reasonably arranged. In particular, double-crop farming in the north should pay more attention to the production season. Secondly, it is necessary to control the water temperature and pay attention to weather forecasts and weather changes. When high or low temperatures occur in the pool water, the water level in the shrimp pond should be raised to more than 1.5 meters in a timely manner, and can reach more than 2 meters if conditions permit. At the same time, attention should be paid to the increase or decrease in water inflow.

(2) Dissolved oxygen. The dissolved oxygen content in the pond water is an important indicator reflecting the water quality of the shrimp pond. The dissolved oxygen content of pond water where Japanese prawns normally grow is generally around 4 mg/L. In order to ensure that there is sufficient dissolved oxygen during the breeding process, the density of seedlings should be reasonably arranged, the feeding should be reasonable, the amount of water exchange should be adjusted, mechanical oxygenation should be added, and oxygenation agents should be used for emergency rescue.

(3) Salinity. The suitable salinity for Japanese prawns is 15‰~35‰. If the salinity is below 7‰, they will gradually die. During the breeding process, appropriate measures should be taken to regulate salinity according to actual conditions.

(4) pH value. During the breeding period, the pH value of the pond water should be controlled at 7.8-9. Shrimp ponds with a low pH value can be adjusted by adding quicklime. Generally, the dosage per time is 2×10-5~2.5×10-5 before mixing with water.

(5) Water color and transparency. The transparency of the breeding pond water should be controlled at 30 to 40 centimeters in the early stage, and 40 to 50 centimeters in the middle and later stages.

Better water colors include yellow-green, tea-green, tea-brown, etc. Bad water colors include dark brown, soy sauce color, milky white, clear color, etc.

Measures to improve water color and transparency include changing water, fertilizing, applying drugs, etc. If harmful water color appears, 5×10-7 to 7×10-7 copper sulfate can be used. For shrimp ponds where shrimp deaths have occurred, 5×10-6 to 6×10-6 bleaching powder should be used for disinfection.

5. Daily observation

(1) Shrimp feeding situation. Feeding status reflects whether the bait is appropriate and whether the substrate and water quality are normal, which directly affects the growth and health of the shrimp.

(2) Shrimp growth. The observation of growth mainly includes the estimation of survival number and average weight, body length measurement and molting status.

(3) Shrimp activity. Observe the activities of Japanese shrimp based on their living habits. If any abnormal conditions are found, such as the shrimp not burrowing in the sand, reduced mobility, slow reaction, floating head or spinning on the water surface, etc., timely measures should be taken to deal with it.

(4) The bottom quality and water quality of shrimp ponds. Including the color and smell of the pool bottom, daily observation of water quality indicators, etc.