Preparation of cultured Penaeus vannamei before stocking

The preparation work before stocking of Penaeus vannamei is mainly to renovate shrimp ponds, drainage and irrigation systems and other production facilities, drug cleaning ponds and culture basic bait, etc.

I. arrangement of shrimp ponds

(1) tanning pool

The aim is to restore the bottom of the pool. In general, the shrimp ponds should drain the water after harvest and let it be exposed to the sun until the sediment is cracked. The sun pool varies from 15 to 30 days, or even 45 to 60 days by using the empty pool time in winter. Then it will be treated according to the pollution degree of the bottom of the shrimp pond.

1. If the bottom soil sludge is 3~10cm thick, the pond water should be drained, the bottom of the pond should be exposed to make the soil oxidize, and then quicklime 100~150kg/ mu should be applied.

2. If the subsoil sludge reaches more than 10~20cm, the bottom soil can be ploughed with cattle plough or mechanical ploughing after the above treatment, so that the lower sludge can also be exposed to sunlight, so that the reduction situation is better. Then sprinkle lime 100~150kg per mu.

(2) Flushing

If the pool water cannot be drained, it should be soaked and washed through repeated irrigation and drainage.

(3) change of soil

If the pollution of the bottom of the pool is too serious and it is difficult to dry or wash, the aged soil on the bottom of the pool can be dug up and transported, and the new sand mud 8~10cm can be filled back. The cost of this method is high, but its effect is good.

Second, medicine to clear the pool

After finishing the above shrimp ponds, wash them with tide water for 3 times, until there is no rust water in the shrimp ponds, the pH of the pond water is stable above 7.8, and then clean the pond with medicine. If the bottom of the shrimp pond is acidic, lime should be added properly to neutralize the acidity, so that the pH value of the pond water is stable, and then clear the pond with medicine.

The purpose of clearing the pond is to kill pests, including fish, shrimp and germs. If raising shrimp for many years, the shrimp pond pollution is more serious, the ditch also has varying degrees of silt accumulation and pollution, per mu shrimp pond first apply quicklime 100~150kg or bleaching powder 30x 50 × 10-6 disinfection, the main purpose is to kill the subsoil and water in the pathogenic bacteria and enemy organisms, lime can also improve the shrimp pond sediment and adjust the pH value of the water; then use tea seed cake or trichlorfon, permethrin and other drugs to clear the pond. Permethrin has a very significant effect on killing white shrimp (commonly known as five-bearded shrimp), usually with a concentration of 0.1 × 10 ~ 6. Five-bearded shrimp is an enemy, it will attack shrimp seedlings or molting prawns.

Third, water intake

The floodgates can be opened to enter the water 2-3 days after the medicine is cleared. It should be discharged several times to dilute and discharge the residual poison of the drug.

A filter screen is set up at the intake gate to filter sea water. The filter screen is made of 60 mesh nylon thread or nylon sieve silk to make a straight plate mesh or a conical mesh. For shrimp ponds with large area, a conical net should be used, which is 5 to 6 times longer than the width of the net mouth. Before opening the gate, check whether the gate and filter screen are installed, whether the gate slot is leaking, and remove debris or sand at the bottom of the gate. The outer sluice slot is equipped with a large mesh (about mesh lcm) straight net to stop sundries. When entering the water, the height of the gate should be determined according to the bearing capacity of the filter, so as to prevent the gate from breaking through and entering the enemy. If the net breaks into the enemy, you should re-use medicine to clear the pool.

30~40cm is suitable for the first influx of water to facilitate fertilization to cultivate food organisms, and then gradually raise the water level.

IV. Food biological culture

Cultivating breeding bait organisms (basic bait) in shrimp ponds is an effective measure to solve the palatable bait of shrimp seedlings and accelerate the growth of prawns. It is also one of the effective ways to make full use of the natural productivity of shrimp ponds and reduce the cost of shrimp culture. Because the basic food organism has the advantages of fast reproduction, simple and feasible culture method and obvious nutritional effect, it has become an indispensable production link in the breeding process. Practice shows that if the basic bait is rich, shrimp seedlings can grow to about 8 cm in a month.

The climate in Guangxi is warm, and the food organisms proliferate rapidly. After about 7 days, the food organisms can reach a considerable density. After fertilization, the concentration of food organisms is mostly expressed by transparency, and the general transparency should be controlled at 30-40 cm. Considering that the bottom material of shrimp ponds along the coast of Guangxi is mostly acidic soil, the effect of organic fertilizer is better than that of inorganic fertilizer. The specific measures are as follows:

After clearing the shrimp pond, store water 30cm and apply fertilizer to the shrimp pond, each time: nitrogen fertilizer 1 × 10-6, phosphorus fertilizer 0.1 × 10-6. Fertilize every 2-3 days to keep the water yellowish green or yellowish brown. And gradually add water to 80 cm, the transparency of the water is controlled at 30 cm to 40 cm. In order to avoid the singleness of food organisms, the food organisms should be introduced into the water regularly so as to diversify the diet of prawns. Fertilization in shrimp ponds should be less and diligent, so as to achieve the "three no application", that is, no application in cloudy and rainy days, no application in the middle and late.

The commonly used nitrogen fertilizers are urea, ammonium sulfate, etc.; phosphate fertilizers include calcium superphosphate and Thomas phosphate; organic fertilizers can be used with chicken manure and cow manure. The ratio of nitrogen to phosphorus is 10 ∶ 1. When applying fertilizer, it is necessary to stir and dilute the nitrogen fertilizer and phosphorus fertilizer respectively, and then sprinkle them evenly. Fertilization was applied once in 3-5 days in the early stage and once in 7-10 days in the later stage. If there are sufficient and abundant bait organisms in the water body, the shrimp seedlings can be fed artificially after 8 cm, depending on the stocking density of shrimp seedlings.