NOTES WHEN REARING SHRIMP IN WINTER

Factors to keep in mind when rearing shrimp in winter

Vannamei is easy to rear, has a high survival rate, and is widely farmed today, but it is also very sensitive to environmental factors. Especially when raising shrimp at the end of the year which environment is included cold weather, heavy rain, and salinity decrease…affect shrimp health.

Breeding white-leg shrimp in winter is very difficult, but if you choose the right time in different farming system conditions, the profit is quite high. Successful winter shrimp farming will bring great economic value, 1.5-2 times more effective than main crop farming and a favorable market.

1. Environmental factors affecting rearing shrimp in winter:

• pH: In shrimp ponds, it should be maintained from 7.5 to 8.5 and the day-night variation should not exceed 0.5 units. In heavily alkaline soil to prevent low pH, it is necessary to spread calcined lime (CaO) on the pond bank and continue to spread lime after rain.
• When it rains heavily, the salinity of the surface water layer decreases rapidly, it is necessary to drain the surface water so as not to cause too great a change. Large ponds and high depth will also help reduce salinity fluctuations during prolonged heat or heavy rain.
• Dissolved oxygen: oxygen in shrimp ponds should not be lower than 4mg/l; if oxygen is lower than 3mg/l shrimp will stop eating and pull to the shore; If not handled promptly, shrimp may die. In addition to increasing fan and aeration, hydrogen peroxide (H₂O₂) can be used.
• Alkalinity: Alkalinity in shrimp ponds must always be kept stable with a content higher than 80mg -CaCO₃/l. During winter shrimp farming, especially in the rainy season, it is recommended to regularly apply lime CaCO3 or Dolomite CaMg(CO3)₂.
• Clarity: Transparency shows phytoplankton growing in shrimp pond water, clarity should be maintained in the range of 25-40cm. Phytoplankton clarity improves shrimp well, because they limit suspended substances, improve shrimp visibility, and reduce hazards to shrimp.
• H₂S (hydrogen sulfite): H₂S is very toxic to shrimp, concentrations above 0.02mg/l affect shrimp; but H₂S only appears when the pH is below 7. Therefore, it is necessary to maintain the pH of the pond water at a neutral level.
• NH₃ (ammonia): NH₃ is very toxic to shrimp when the concentration of 1mg/l can cause the death of shrimp, a concentration above 0.1mg/l affects the growth of shrimp, so it is necessary to maintain NH3 below zero. ,1mg/l in many ways, but some microbial products can be used to absorb them in the last months of the culture cycle to absorb less NH3.
• The pond bottom is black, the water is cloudy with many suspended substances: At the end of the winter shrimp farming cycle, the pond bottom often accumulates a lot of organic matter and H2S, and there are many suspended substances in the water due to dead algae; can use microbial products, Zeolite to absorb suspended substances and residues in the pond.
• The appearance of gerbera, dog’s foot fungus in farming ponds (Among ponds, tarpaulins, ..): At the time of the season change, when the temperature is low, rain is abundant, algae are gone, the pond contains a lot of organic matter. This is a favorable condition for the coin fungus to grow. Not only that, but this species also clings to tarpaulins, water fans, buoys, and farming tools, seriously affecting the health of farmed shrimp when they are eaten. Therefore, it is necessary to use mechanical or biological measures, and chemicals to inhibit and prevent their occurrence.

2. Select white shrimp varieties for the winter crop:

Select healthy post 12-15 post-larvae, clear origin, and certified by the competent authority. Farmers should note that in the winter, there are many production facilities that transport small-sized shrimp, sometimes only post 5-6, if farming will prolong the time.

Therefore, do not choose shrimp post 5 – 10. The stocking density does not exceed 80 – 120 shrimp/m2. Whiteley shrimp can be reared first in an indoor nursery tank to shorten the time spent outside. Stocking density: 2,000 – 2,500 shrimp/m2 after 25 – 30 days of rearing time, when shrimp reach size 1g/head, proceed to transfer shrimp to grow-out ponds.

• Stocking

Monitor weather developments to choose the right drop time. Seeds should be stocked before cold air for about 4-6 weeks (at this time, the weather is sunny and shrimps grow fast). Stocking should be avoided during monsoons, and prolonged rain, it is necessary to balance the water temperature in the seed bag and the culture environment before stocking (soak the seed bag for about 15-20 minutes in the pond water).

3. Care and management

Manage to feed and monitor the ability of farmed shrimp to catch prey to avoid overfeeding. When the temperature is low, it is necessary to reduce the amount of feed both in quantity and in the frequency of feeding; Feed 2-3 times per day. Check the molting cycle of vannamei shrimp in the pond to adjust the amount of feed. Check the sieve to adjust the feed to suit changes in temperature and weather as well as shrimp health status.

During the initial period of small shrimp (1 – 3 weeks), aeration is mainly used. Use a water fan from week 4 onwards. Periodically check environmental factors daily at 5-6 am and 14-15 pm. If the index of environmental factors is outside the appropriate threshold, measures must be taken immediately.

4. Disease prevention and treatment in winter shrimp farming

Regularly observe, monitor, and check the health status of farmed shrimp for timely handling measures.
Especially in cold weather, parasites, and microspores-EHP are the most worrying pathogens. Therefore, the application of preventive measures from the beginning of the farming season to ensure the health of farmed shrimp is extremely necessary. People should add probiotics to their shrimp diets, which help ensure shrimp growth and health, limit damage and improve crop productivity.

Proposed solution from Thai Nam Viet:

THAI NAM VIET provides solutions for probiotics, and enzymes with high content and strong activity to meet shrimp farming activities in the winter crop. By competing with harmful Vibrio in terms of nutrition and living space, Thai Nam Viet’s microbial strains bring strong efficiency in decomposing excess organic matter, creating a safe and stable living environment. designated for domestic animals.

From there, the use of probiotics will solve the target problems and ensure shrimp growth and health, limit damage and improve crop yields.