The cultivation of healthy seedlings is a guarantee for the cultivation of high-quality shrimp seedlings. Only healthy seedlings can be cultured to enable farmers to obtain better economic benefits. The following are some key technical aspects of the production of healthy seedlings of Penaeus vannamei:
I. Disinfection of the production of nursery water to control and eliminate pathogens. With the deteriorating breeding environment, the virus and bacteria in the waters of the sea area have also increased, which has severely affected shrimp rearing. Therefore, disinfection of seawater is one of the effective measures to ensure the success of shrimp breeding. The main approach: the sea water drawn from the sea area enters the reservoir for precipitation. After 24 hours, the seawater filtered by the sand filter is filtered by a nylon screen mesh of 80 mesh to 120 mesh, and then enters the pool. Then, disinfect the nursery water, you can directly pass the chlorine, you can also add sodium hypochlorite, bleach or bleach, so that the available chlorine content in the water (15-20) g/m3, after 12h, add sodium thiosulfate to remove Excess chlorine.
Second, we must improve and optimize the cultivation of the environment.
1, scientific and reasonable larval rearing density. The larval rearing density of larval rearing depends on different periods of shrimp development. Too little or too dense is not conducive to the regulation of water quality and the feeding of diets, and it is easy to form a stress environment and easily induce diseases. Reasonable cultivating density: no hatchling period (30-35) 10,000 tails/m3 water body; zoea larval stage (25-30) 10,000 tails/m3; larval period of pupae shrimp (15-20) 10,000 tails/m3; prawns Period (10-15) 10,000 tails/m3.
2, timely and appropriate use of beneficial microbial agents. The use of viable organisms in nursery waters is mainly used in the early stage of seedling rearing, so that the water environment can form advantageous beneficial populations and inhibit the reproduction of pathogenic organisms. The method of use is as follows: Prior to the hatching of the nauplii, the cultivation tank is to receive 2 billion/g of vitamins (bacillus) and 5ppm of photosynthetic bacteria at 10ppm, and add 3ppm photosynthetic bacteria per day during the zoea period, and add it every day during the pupa period. Bacillus 2ppm until the fifth day of prawns, ie P5.
3, the rational use of water conditioners, and make full use of the sun. When the larvae develop into the larvae of the mandarin shrimps, 3 ppm-5ppm of water quality improver such as zeolite powder can be put to purify the water, adsorb harmful substances, increase the appetite of the lobster shrimp, and open the shade cloth on the pool surface to make full use of the sunlight to make the water of the nursery water. Forming a virtuous circle and achieving a balance of algae will not only save the cost of bait, but also allow the larvae to develop healthily.
Third, seriously prevent disease during nursery.
1. Strengthen the nutritional management of broodstock and regularly eliminate inferior broodstock. The combination of a variety of high-quality live bait feeds is a successful experience in the cultivation of broodstock. Live sand cod, squid, and fresh oysters are ideal baits. Feeding should be fed on time and in appropriate amounts, with multiple meals and more feeding to meet the principle of broodstock feeding. The broodstock breeder feeds 25% of the weight of the broodstock each day. Feeding at regular intervals four times a day, 6:00 am to 7:00 am, 12 pm, 6 pm, and 8 pm, once in the morning, feed in the morning and afternoon, and account for about 3/5 of the total feeding amount. Check broodstock feeding conditions and adjust feed intake. Once found poor feeding, physical decline in broodstock should be regularly eliminated in order to improve the quality of broodstock spawning. Penaeus prawn is best used for no more than half a year.
2. Establish a system for the prevention of disease isolation and strictly regulate disinfection management measures. First of all strict disinfection, broodstock cultivation pool, spawning pool, shrimp cultivation pool and tools before using bleaching powder 80ppm-100ppm or potassium permanganate 40ppm-50ppm for disinfection, the use of tools to be dedicated pool dedicated personnel dedicated. Probiotics should be sterilized with povidone-iodine 20ppm-30ppm for 3min-5min before entering the pond or before spawning. The second step is to isolate the diseased shrimp and take corresponding measures.
3. It is forbidden to raise seedlings in high temperature to improve the immunity of shrimp seedlings. The temperature of ripening cultivation of broodstock is controlled between 28 °C and 29 °C, and the temperature of shrimp cultivation water is controlled between 25 °C and 30 °C.
4. Observe the activities of the shrimp seedlings during the cultivation of the shrimp seedlings. If any problems are discovered, deal with them in time, use less drugs, and do not use the national banned drugs.
Fourth, do a good job of breeding and management of shrimp seedlings.
1. Methods and precautions for feeding of Skeletonema. First of all, the cultivated Skeletonema must be tested. The algae used for culturing the shrimp seedlings are best harvested at the peak of growth. When feeding, the 60 mesh mesh bag is used for rinsing and feeding. At this time, the concentrated liquid has a fresh algae scent. After the peak of growth, the body color of Agaricus is aging and deteriorating, which has a toxic effect on larvae and should not be fed. Secondly, the conservation measures of Skeletonema are established. Under the microscope, the enlarged spores of Skeletonema are selected for purification and rejuvenation.
2. Pay attention to the use of insects. First of all, we must strictly disinfect and immerse and sterilize with strong chlorine extract 80ppm-100ppm for 10min-15min before incubation. Secondly, Fengnian insects must be hatched with high-salinity seawater, completely and completely separate Artemia nauplii from shells and dead eggs, and prevent insect shells and dead eggs from damaging and transmitting diseases to the larvae.
3, artificial bait feeding. The larval bait is mainly composed of shrimp slices, ie, artificial baits such as Bp and black granules, and is fed with bio-feeds such as Skeletonema elegans and Artemia elegans. The feed is fed 5 times a day. The bait is fed on a small quantity basis, according to the water color and feeding. The situation, the remaining food, flexible adjustment of the amount of food.
4, establish a sound water quality monitoring procedures. Through the monitoring of various parameters of water quality, water quality can be adjusted in time. The main parameters are: pH value 7.9-8.5, ammonia nitrogen less than 0.6ppm, nitrite less than 0.1ppm, water temperature 25°C~30°C.
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