Key Points for Winter Pond Management

In winter, as water temperatures drop, fish activity decreases, their feed intake reduces or stops altogether, and their survival largely depends on the pond environment, the health of the fish, and the management practices of the farmers. Improper management during winter can lead to significant fish mortality, directly impacting the economic interests of farmers. Below are key management tips for winter ponds, focusing on water temperature, feeding, stocking density, and disease prevention.

1. Maintain Stable Pond Water Temperature

During winter, the water temperature should be kept between 16-20°C. If the temperature drops too low, fish feeding decreases, they lose weight, and become more susceptible to disease. To maintain a stable temperature:

• Increase the temperature: Use the heat generated from fertilizer fermentation and decomposition to warm the water.
• Add aquatic plants: Place water plants in the pond for fish to shelter from the cold.
• Add sun-warmed water: On sunny days, add shallow, sun-warmed water to the pond in the afternoon to raise the temperature.

2. Scientific Feed Management

Although fish activity is minimal in winter, they still have some feeding capacity. Feeding should be managed according to the weather, water temperature, and fish activity levels. Timely and appropriate feeding enhances the fish's body condition, reduces weight loss, and improves winter survival rates. Additionally:

• Apply fertilizer moderately: This helps maintain nutrient levels in the pond, enhances the fish's body condition, and increases cold resistance.

3. Pond Management During Winter

Daily inspections should be conducted in the early morning, midday, and evening to observe water color and fish activity. Regularly monitor water quality indicators, especially oxygen levels. When oxygen levels are low, implement aeration measures, such as adding new water. In case of oxygen depletion:

• Use an aerator or pumpto oxygenate the water.
• Apply oxygen-enhancing agentsif necessary.

During winter, aerators should be used based on weather, water temperature, and feeding conditions. If low atmospheric pressure leads to fish surfacing for air, increase the aerator's operating frequency and duration.

4. Appropriate Stocking Density

Overstocking during winter can lead to oxygen depletion and increase the risk of fish diseases. Therefore, timely harvesting is essential to reduce stocking density and ease the load on the water. The stocking quantity and fish species ratio should be adjusted according to the pond's conditions. Additionally, stirring the pond:

• Use bamboo poles to stir the pond bottomon sunny afternoons, periodically stirring different areas of the pond.

5. Winter Fish Disease Prevention

In winter, fish immunity decreases due to the cold, making them more susceptible to diseases, which can cause significant economic losses. Common winter fish diseases include:

• Trichodinosis: Trichodina invades the fish's gills and skin, forming a gray mucus layer. Treatment includes a mixture of copper sulfate and ferrous sulfate applied to the pond. Regular feeding with medicated food can also prevent parasitic diseases.
• Dropsy (Scale Erection Disease): This disease mainly affects fish after winter when they are in poor condition with weakened immunity. Infected fish become lethargic and struggle to breathe, dying within 2-3 days. Treatment includes water changes every 3-5 days and the application of medication to improve antioxidant capacity and boost the immune system.
• Ichthyophthirius: This parasite causes excessive mucus secretion on the fish's skin and gills, leading to respiratory difficulties and death. The treatment method is similar to that for Trichodinosis.
• Saprolegniasis (Water Mold Disease): Infected fish develop white fungal filaments on wounds, resulting in sluggish behavior, poor appetite, and death. Treatment involves applying antifungal agents to the entire pond, which disrupts the fungus and enhances the fish’s immune system to speed up wound healing.

These key management points will help ensure the successful overwintering of fish and minimize economic losses.