CATDOLL : CATDOLL: How to raise shrimp fry with a high survival rate?

1. How to increase the survival rate of shrimp fry?

Stocking shrimp fry includes stocking shrimp fry into temporary holding ponds and directly stocking shrimp fry into grow-out ponds. Stocking shrimp fry is the first step in raising shrimp well. Improper handling will reduce the survival rate of shrimp fry, or even kill all of them, affecting the growth effect. Therefore, stocking shrimp fry is a very important production technology link in the shrimp farming process. In order to improve the survival rate of shrimp fry, the following conditions must be met when stocking shrimp fry:

(1) Water environment of shrimp pond The water depth of the culture pond is 40-70 cm, the water quality is rich and active, the water color is normal, and the green, yellow-green or brown-green color is formed by green algae, diatoms and golden algae as the dominant algae. The transparency is 30-40 cm, and there are no harmful organisms such as ciliates and naked dinoflagellates. There is no excessive reproduction of filamentous algae and channel algae. The water temperature of the shrimp pond should be as consistent as possible with the original water temperature of the nursery pond, and the temperature difference generally does not exceed 8℃, and the water temperature should be kept within the suitable temperature range for the shrimp fry, such as above 14℃ for Chinese shrimp, above 16℃ for Japanese shrimp, and above 20℃ for giant tiger shrimp. The salinity of the shrimp pond should be suitable for the survival and growth of shrimp fry, and the difference between the salinity value of the shrimp pond and the shrimp fry should not exceed 5. If it exceeds the range, acclimatization treatment should be carried out. The pH of the pond water should be between 7.8 and 8.7. If it exceeds this range, it should be solved by changing the water or adjusting the pH with lime or other pH regulators.

(2) Weather conditions: The temperature is suitable, there is no cold current, no heavy rain, and no strong wind. In addition, the following matters should be noted when stocking shrimp fry:

① After the shrimp fry are transported back, their survival, quality and quantity during transportation should be carefully observed. If conditions permit, they can be re-counted and put into the pond. The shrimp fry (small fry) can be placed in a net cage with a mesh size of 1 to 2 mm first, and after 4 to 5 hours of adaptation, they can be re-counted and put into the pond.

② After the shrimp fry are transported back, the canvas bucket or nylon belt should be opened immediately and some fresh pond water should be poured in to avoid death due to oxygen consumption during transportation. At the same time, the container should be placed in the shrimp pond to allow the temperature and water quality environment to transition, and then the shrimp fry should be poured into the shrimp pond or the net cage in the pond at the appropriate time.

③ Note that the seedlings should be transplanted in the upwind area of ​​the pond and in clear water to reduce losses.

④ At the same time as releasing the fry, it is best to release 50 to 100 shrimp fry at the same density into the net cages in the pond (the draft should be deep), feed them for 3 to 5 days, and track and observe their survival to further judge the quality of the shrimp fry, so as to infer the survival rate of the shrimp fry in the shrimp pond.

⑤ Stock enough shrimp fry in the same shrimp pond at one time to avoid multiple replenishments.

This article is from: China Agricultural Press "Protecting Natural Resources"

2. Where can we find tiger shrimp fry in Guangdong?

Niuguwan is rich in giant tiger prawns, Japanese flower prawns, etc. The shrimp meat is delicious, tender and juicy. No matter it is steamed, steamed with vermicelli in garlic sauce, pan-fried or braised in tomato sauce, it is so delicious and pleasant, leaving you with endless taste buds.

3. What are the prevention and treatment methods for white spot disease in crayfish? What are the requirements for breeding technology of giant tiger prawns?

It is the peak sales season for crayfish again, but this period is also a more troublesome period for farms, because during the Beginning of Summer, the climate is warm and humid, the temperature fluctuates, and there is a lot of rainfall, which is very easy to cause various diseases for crayfish breeding. Below, taking the common white spot disease of crayfish as an example, let's take a closer look at the causes, symptoms, and targeted prevention measures of white spot disease of crayfish. Compared with healthy crayfish, crayfish with white spot disease have reduced activity and reduced food intake, and their bodies are also filled with water.

If you try to peel the shell by hand, you will find that it is easy to fall off. In addition, the liver of the crayfish will turn white. The most obvious sign of illness is that there are oval white spots on the surface of the shrimp shell. The guarantee of good water quality can bring certain preventive and therapeutic effects. You should pay more attention to the disinfection and cleaning of the pond. In terms of feeding, it is recommended to feed full-price concentrated feed, plus antiviral drugs or concentrated feed with immune accelerators, which can enhance the immunity of crayfish.

During a period of sustained high temperature or when the ambient temperature changes significantly, the crayfish will eat a lot during this period, but be careful not to overfeed, which will cause excessive nutrition or accumulation of concentrated feed. Maintain the water level and pay attention to the temperature stress caused by drastic changes in water temperature. At the same time, you must also pay attention to the stocking density. Avoid frequent fishing of crayfish to avoid disturbing the crayfish too much and causing overreaction. There are no obvious symptoms in the early stage, only little activity, slow behavior, and significantly reduced food intake. In the middle and late stages, water accumulates in the body, the head shell is easy to fall off, there are white spots on the head and chest, and the muscle tissue turns red. It quickly spreads and dies on a large scale, and even infects river shrimp.

During the period of continuous high temperature, especially after a long period of rainy days, a large number of phytoplankton die, the water surface turns blue, and plankton such as rotifers multiply in large numbers. The water body and bottom mud are seriously polluted, and the pond mouth stops oxygenating due to power outages or equipment failures, making shrimps susceptible to the disease. The size of crayfish is not related to high pathogenicity, but only when the individual grows to a relatively large size can it eat the media microorganisms carrying the virus. In addition, crayfish have the habit of cannibalism, and the white spot disease virus infection has a strong high pathogenicity. The main infected cell tissues have no selectivity, such as the infection rate of the dermal cells under the hard shell is as high as 100%, resulting in the inability of the above cell tissues to be compensated, which can cause the death of crayfish in a short time.

The prevention and control method can be a good water environment, which can ensure a certain preventive and therapeutic effect. We should pay more attention to the water environment. High temperature is also one of the prevention and control methods for crayfish. Maintain water depth and pay attention to changes in surrounding water temperature.

1. A good water environment can play a certain preventive and therapeutic effect. Usually, you should pay more attention to the disinfection and cleaning of the pond. In terms of feeding, it is recommended to feed complete feed and add antiviral drugs or immunostimulants to the feed to enhance the body immunity of crayfish. 2. During high temperatures or when the temperature changes significantly, the crayfish eat a lot during this period, but do not overfeed, which will lead to excessive nutrition or feed accumulation. Shrimp seedlings are required to be uniform in size, strong and energetic, have good upstream swimming ability, have a smooth body surface without attachments, and be more than 0.9 cm long. After virus and Vibrio testing, they must not carry several specific pathogens such as WSSV, TSV, IHHNV and IMNV, and the number of Vibrio is within a safe range.

The methods required for treating white spot disease of crayfish include the important requirements for water and food. The breeding technology of tomato shrimp has high technical requirements and requires strict control of water and soil.

4. Can I put shrimp fry in the pond water with 1 degree salt?

Under artificial breeding conditions, the suitable water temperature for whiteleg shrimp is between 16 and 35°C.

(gradient range), the optimal growth temperature is 25~32°C. Related studies show that juvenile shrimps weighing about 1 gram grow fastest at 30°C, while large shrimps weighing 12~18 grams grow fastest at 27°C. The minimum temperature for the cultivation of white shrimp should be above 18°C. When the water temperature is below 15°C, white shrimps will reduce or stop feeding; when the water temperature is below 9°C, they will lie on their side or die; when the temperature is above 35°C, the feeding and growth of white shrimps will be greatly affected.

What is the appropriate salinity for shrimp farming?

Prawns are generally euryhaline species, which can adapt to a wide range of salinity. Chinese shrimp can survive and grow in brackish water with a salinity of 1 and seawater with a salinity of about 40. The giant tiger prawn can survive in waters with a salinity of less than 0.5. The black shrimp cannot survive in waters with a salinity of less than 7. Postlarvae and juveniles can often tolerate lower salinity than adults. Prawns cannot survive in pure fresh water.

The adaptability of shrimp to temperature and salinity can be domesticated. The gradual transition method can make shrimp adapt to larger temperature and salinity differences. Usually, the range of adaptation after domestication is related to the temperature or salinity of the shrimp before domestication, and to the speed of domestication. Slow domestication can increase the range of adaptation.