(2) Non-high-temperature cultivation (high-temperature seedlings above 32℃), the seedling raising period is generally about 20 days;
(3) Select seedling manufacturers with less drugs, use microbial agents to adjust the water quality, and use more biological bait (generally used by rotifers and mature larvae);
(4) The specifications shall be neat and the individuals shall meet the stocking standards. The smaller the individual difference of the same batch of shrimp seedlings, the better the quality. It is best to reach about 0.8 cm for Penaeus vannamei, and above 0.6 cm for urgent use.
(5) By naked eye observation, the shrimp colony is well developed, the muscles are full and transparent, the appendages are normal, the body segments are slender, the tail fan is fully extended, the gastrointestinal tract is full of food, the swimming is lively, the swimming ability is strong, and there are no external parasites and attached dirt.
How to investigate the vitality of prawn fry? (1) Put your hand into a basin filled with water and shrimps, and healthy shrimps will immediately escape the pressure, while poor shrimps will be slow or unresponsive.
(2) Turn the water clockwise or counterclockwise by hand, so that the water forms a vortex and the shrimps are concentrated in the center. When the water flow is a little slow, healthy shrimps will spread out and swim against the current, otherwise they will be unhealthy shrimps.
(3) Take a batch of shrimps (about 100) and put them in a wet towel and let them stand for 10- 15 minutes to check their survival rate. The higher the survival rate, the better the quality of shrimp. If necessary, first take a batch of shrimp seedlings and try to raise them in the shrimp pond for two or three days, and then send them to relevant units for testing whether they carry the virus.
How to put the seedlings? The optimum water temperature for the growth of Penaeus vannamei seedlings is 22℃-35℃. In this water temperature range, the cultured shrimp seedlings grow fast, eat a lot, have strong physique and strong disease resistance.
(1) stocking density: 40,000-80,000 fish/mu in semi-intensive shrimp ponds, 80,000-65,438+/kloc-0,000 fish/mu in intensive shrimp ponds, and 0,000-300,000 fish/mu in small and high-grade intensive shrimp ponds. The specific stocking density depends on pond conditions, aquaculture technology and management level. ?
(2) Matters needing attention in shrimp seedling feeding:
(1) The water quality indexes of nursery ponds and aquaculture ponds should not change too much. Water temperature change
(2) Spraying "Ke Jun 27" about 2-3 mu/bottle the day before seedling release to maintain an excellent water quality environment. Pay attention to detoxification and stress resistance before releasing seedlings, and sprinkle "oligosaccharide 863", "Gianc" or "immune hormone" about 2-3 mu/bag to effectively improve the survival rate of releasing seedlings.
(3) (5) No seedling release: No seedling release until the pond is completely cleaned; Don't plant seedlings in bad weather; If the fertilizer is not good, don't put the seedlings; The water quality index is not suitable for not releasing seedlings; Don't plant seedlings when the water temperature is too low.
(3) Seedling trial planting: the survival rate of trial planting for one day is 90%? The above shows that the seedlings can only be released if there is no problem in the pool water, and it is best to raise them for more than 3 days if possible.
(4) Seedlings releasing method: Seedlings should be released in a sheltered place with deep pool water, and bagged shrimp seedlings should be put into water to adapt for a period of time, and then released after 20 minutes. There are two ways: directly stocking in a big pond, and then putting it into a big pond in the middle.
How to improve the survival rate of shrimp seedlings in ponds? The first molting after seedling release is the most serious loss of shrimp seedlings. Usually, due to the unequal difference between the water quality of the seedling farm and the water quality of the pond, this change of water environment makes shrimp seedlings shed their skin on the day of seedling release. Therefore, "Ke Jun 27" is generally applied one day before seedling release to maintain good water quality conditions; Two hours before the seedlings are released, products such as "Oligosaccharide 863" or "Jiedu Anti-stress Spirit" are sprayed to enhance the anti-stress ability of shrimp; Use "bioactive calcium supplement" or "calcium additive" to accelerate the shell shedding of shrimp seedlings due to stress 5-6 hours after seedling release; The most important thing is to mix a pool of water, cultivate high-quality algae, and provide sufficient natural bait for shrimp seedlings before releasing them.
? Why do prawns have a regular swimming pool after they are released? In the early stage, the concentration of algae was small, and the natural bait of shrimp was less. Due to the lack of bait, shrimp larvae feed in groups, so there is a phenomenon that shrimp larvae swim in groups in the pond. As shrimps are aquatic animals that lie in the daytime and come out at night, a large number of shrimps are exposed to direct sunlight during the day, which is easy to cause physiological stress, reduce the physique of shrimps and affect the survival rate of shrimps.
Solution:
(1) Increase the frequency and quantity of feeding, and try to provide shrimp with enough edible bait.
(2) Use "One Fertilizer" and "Fish and Shrimp Cola" to rapidly increase the content of natural bait such as algae.
(3) Spraying "oligosaccharide 863 with calcium" can reduce the stress of shrimp and promote the rapid propagation of algae.
(4) Adding old shrimp pond water can increase the content of natural bait such as zooplankton, promote the diversity of biological species in the water body and strengthen the stability of the water body.
How to deal with the shrimp pond after jellyfish enter the water? Check whether the water inlet net cover is damaged, and repair or replace it in time if it is found damaged; Sprinkle anti-stress products such as "Ji 'an C" or "oligosaccharide 863" first, and then inject fresh water into the pond for 20-30 cm, and jellyfish will die of stress; If there is no fresh water supplement, 800g/mu of alum or 500g/mu of copper sulfate can be used for the whole pond splashing treatment; After the jellyfish died, spray 500ml/ mu of "green water cut" to detoxify in time, and fertilize the water quality with "one fertilizer+fertilizer water essence+strong EM".