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Winter fish species notes
From the winter solstice to the Spring Festival, fish are in their optimal growth phase. During this period, water quality remains stable, fish bodies are strong, and they are less prone to disease. Their scales are tight, and their adaptability is high, making it an ideal time for stocking. The low water temperature reduces fish activity, which makes handling and stocking easier, resulting in higher survival rates. This also helps avoid the challenges of overwintering in ponds, allowing for earlier evacuation and intensive cultivation. Early spring growth can be promoted, helping fish adapt quickly, start feeding early, and grow faster. However, due to the cold temperatures, special attention must be given to the details of stocking.
Fish pond renovation should begin as soon as possible during excavation or reconstruction. A pond area of at least 2 mu (about 1.33 acres) with a depth of 2 meters or more is recommended. The bottom should have good water retention, no leakage, and access to a clean water source. The location should be sheltered from wind, with good water quality and ample sunlight. For old ponds, follow the principle: “small ponds become large, shallow become deep, dead become living, and leaking become protected.†Each year, remove sludge from the pond bottom, keeping it between 10 cm and 15 cm. After sludge removal, let the pond dry for a few days. Ponds in good condition may also need to be drained, exposed to the sun or frozen, and then deepened and reinforced. Remove weeds, dig out thick sludge, and prepare the pond for the next season.
Pond disinfection is essential to eliminate pathogens. Dry pond disinfection involves using 75–100 kg of quicklime or 3–4 kg of bleaching powder per acre. Mix these in water and evenly spread across the pond. Let the pond sit for several days, then stir thoroughly to ensure full coverage. Alternatively, for wet disinfection, use 130–150 kg of lime or 10–12 kg of bleaching powder per mu at a depth of 1 meter. Be sure to sprinkle along the edges, where mistakes often occur.
Before stocking, apply base fertilizer to newly excavated or thin ponds to promote natural food growth. The amount depends on sediment quality, pond condition, and type of fertilizer. After 5 days of disinfection, fill the pond completely and apply 400–600 kg of human or animal manure per acre directly onto the bottom. Once spring begins, increase feeding to support fingerling growth. Biological fertilizers can also be used to improve water quality.
When stocking fish in winter, focus on four key points. First, seize the right opportunity. Stocking is divided into initial and supplementary phases, and flexibility is important. It’s best to stock around the winter solstice and Spring Festival when water is cooler, fish scales are tight, and survival rates are higher. Second, choose appropriate species based on market demand and water conditions. Fertilizer-rich ponds should focus on herbivorous fish like grass carp, while others may include omnivores. Third, ensure fish quality—strong, healthy, and free of disease, with a minimum size of 13 cm. Fourth, disinfect fish before stocking using 3–5% bleach or 8 mg/L copper sulfate for 10–15 minutes. Larger fish may receive vaccines to prevent disease.
Feeding should start early in winter or spring when temperatures rise. Use nutrient-rich feed, about 1–2% of the total fish weight, and maintain consistent feeding times and locations. Adjust feeding frequency based on weather, water quality, and fish behavior. Proper feeding helps build body fat, ensuring fish survive the winter successfully.
During winter and spring, management should focus on the "four preventions." First, protect the pond from water fluctuations—adjust water levels based on weather. Second, avoid overfeeding by following a timely and moderate approach. Add supplementary feeds like bean cakes during cold periods. Third, prevent disease through regular monitoring and treatment. Use lime sulfate or copper sulfate solutions every half month, and place disinfectants in bait. If disease occurs, consult experts immediately. Common issues like fungal infections can be treated with saltwater baths or antifungal solutions. Finally, manage pond cleanliness by removing sick or dead fish promptly to prevent disease spread and maintain water quality. Regular patrols and quiet surroundings help reduce stress on fish.