Astragalus, commonly known as yellow trout, is a cold-blooded fish that thrives in variable temperatures and has strong environmental adaptability. Its optimal growth temperature ranges from 15°C to 30°C. When the water temperature drops below 10°C, it becomes less active, stops feeding, and enters a hibernation state. To ensure its survival during winter, several effective overwintering methods can be applied.
The first method involves keeping the fish in water during winter. The pond should be maintained at a depth of 30–50 cm to keep the bottom water above 0°C. If ice forms on the surface, it's essential to break the ice daily to prevent oxygen depletion and maintain water quality. This helps avoid hypoxia, which can be fatal for the fish.
The second method is called dry pool wintering. When the temperature drops below 10°C, the pond should be drained until the bottom remains moist. A layer of rice straw, wheat straw, or corn stalks should be spread over the mud, with a thickness of about 30 cm. This provides insulation and helps maintain a stable microclimate for the fish.
The third method involves indoor wintering. When the temperature falls below 10°C, the fish should be moved into an indoor environment. A mixture of 1 kg of astragalus root and 2 liters of water can be used to create a solution in which the fish are placed. The water should be changed daily, and the room temperature should be kept between 2°C and 5°C. This mimics a natural winter environment while ensuring the fish remain healthy.
The fourth method uses a plastic greenhouse. When the outdoor water temperature drops below 12°C, a plastic greenhouse can provide a suitable shelter. The water level inside the greenhouse should be slightly higher than the regular aquaculture level, and the internal temperature should be maintained between 2°C and 8°C. During the warmest part of the day, the ventilation holes should be opened to allow fresh air circulation. Additionally, top vents should be installed to prevent oxygen deficiency, which could lead to jaundice and death in the fish.
By applying these methods, farmers can effectively protect Astragalus during the winter months, ensuring better survival rates and healthier fish for the next growing season. Each technique is tailored to different conditions, making it easier to choose the most suitable approach based on available resources and local climate.
A soil conditioner is a material added to soil to improve its physical properties, fertility, and overall health. Unlike fertilizers, which primarily provide nutrients to plants, soil conditioners focus on enhancing the soil structure and its ability to retain moisture, aerate roots, and support microbial life. They are typically made from organic or natural materials such as compost, manure, peat, or humic substances, but can also include synthetic options like gypsum or polymers.
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