Fish defense cold damage practical technology
Fence guardrails Xuzhou Guifeng Metal Technology Co., Ltd , https://www.guifengmetal.com
July 11 11:24:27, 2025
Fishing pond selection is crucial for successful overwintering. Choose a leeward, sunny winter pond that is more than 2 meters deep to naturally protect fish from cold weather. The water in the overwintering pond should not remain stagnant for long periods; it's recommended to exchange about 1/4 to 1/5 of the water every 20 to 30 days to maintain good water quality and prevent pollution.
To further protect the pond from cold winds, construct a 2-meter-high windbreak using straw or mud on the northern side. Slope the east and west sides in a rounded shape to reduce wind impact. A drainage ditch should also be built around the pond to prevent rainwater from entering and lowering the temperature. Additionally, dig a shelter in the north wall, extending 40 cm from the bottom to a depth of 2 meters and a diameter of 0.8 meters. This shelter can be made with bricks or ceramic tubes, providing fish a safe place to hide during cold spells.
Building a plastic film greenhouse over the pond enhances insulation. Use bamboo or wood to create a "person"-shaped roof above the pond, keeping the distance from the ground to the roof at about 2.5 meters. Cover the structure with two layers of plastic film, sealing the edges with mud. These greenhouses are typically 40 to 100 square meters in size, with water depths exceeding 2 meters. Stocking density depends on water temperature, quality, and volume—usually around 15 brood fish per cubic meter or 25 tails, and up to 300 fish under 10 cm in size. In better conditions, 30–40 brood fish per cubic meter can be kept, along with 400–500 smaller fish. Flow-through systems can follow high-density stocking practices.
Maintain dissolved oxygen levels at 2 mg/L to ensure fish health. Without proper insulation, outdoor overwintering can lead to 70–80% mortality. Therefore, moving fish indoors or covering outdoor ponds with plastic greenhouses is advisable. Stocking density in such cases should be about 100 fish per square meter. With proper management, survival rates can reach 80–90%. During colder nights or rainy days, cover the greenhouse with thick grass curtains to retain heat. On sunny days, open straw huts or other structures to allow solar warming. If the water becomes too warm, ventilate and replace some of the water.
In case of sudden temperature drops, immediately replace the water or use heating methods. Cold waves often bring prolonged low temperatures and rain, which can deteriorate water quality and cause diseases like anchor worm infestations. Besides changing water and using aerators, apply microbial treatments regularly. Insecticides should be used promptly to control pests and prevent their spread.
Feeding during winter is essential, even though fish metabolism slows down. The goal is to keep fish healthy and prevent frost damage, not to promote growth. Feed should be nutritionally balanced, focusing on amino acids, vitamins, and minerals rather than just high protein. For tilapia, feed can include glutinous rice, bran, bean cake, and malt, supplemented with fresh greens. Before and after wintering, boost energy and protein intake by increasing fat content by 3–5% and feeding as much fresh food as possible. Add targeted vitamins, calcium, and phosphorus to improve resilience and cold tolerance. B vitamins, vitamin A, D, E, and choline are especially important during winter, so they should be included in higher amounts to support overall health and disease resistance.
A fence railing is a structure used to protect and define private or public spaces. It is usually made of different metal materials and is installed around the perimeter of a building, site or area to prevent unauthorized entry or to provide additional security. Fence railings are designed with aesthetics, functionality, and cost in mind.
1. Security & Privacy: Fences prevent outsiders from entering, protecting the safety of occupants or users, while providing a certain amount of privacy to the interior space.
2. Aesthetic decoration: With different designs, materials, and color options, fence railings can become a part of the landscape and enhance the overall aesthetic appeal.
3. Boundary Definition: Clearly define the boundaries of a specific area to help people understand what is accessible and what is restricted.
4. Wind and rain protection: In some areas, fence guardrails can also play a role in wind, rain protection, and protect the building from bad weather.
Material Type:
- Metals: such as wrought iron, aluminum alloy, etc., with strong durability and relatively low maintenance costs.
Design & Installation:
- Height: Depending on the purpose of use and regulatory requirements, the height of the fence guardrail may vary.
- Spacing: The spacing between the vertical rods is less than 110mm.
- Material strength: Ensure that the material chosen can withstand the expected environmental conditions and potential impact forces.
- Installation: Consider the ground foundation, soil conditions and terrain characteristics to ensure firm and stable.