The scientific name of the river crab is *Eriocheir sinensis*, commonly known as the Chinese mitten crab. It is highly valued for its delicious meat, rich nutritional content, and medicinal properties. Due to its high market demand, especially in China, it offers significant economic returns and promising breeding potential. If you're interested in raising crabs in northern regions, here are the key steps and considerations:
First, selecting quality seedlings is crucial. The best source for high-quality seedlings is the Yangtze River system. Crabs from the Liaohe or Zhejiang systems are not recommended for introduction due to lower adaptability. Before purchasing, ensure that the seedlings undergo strict quarantine procedures and avoid any that show signs of disease.
Second, there are two main breeding methods: pond culture and rice field farming.
1. **Pond Intensive Culture**:
- **Pond Selection and Preparation**: Choose a pond with a clean water source, stable water level, no pollution, and good water clarity and dissolved oxygen levels. Include aquatic plants like grasses and snails to support the ecosystem.
- **Stocking**: Disinfect the pond for 15 days before introducing seedlings. It's best to release them on rainy days or during cooler morning and evening hours. For second-stage juvenile crabs (around 5g), stock 2000–3000 per acre. Adult crabs should be stocked at 0.8–1 kg per acre. You can also add a small amount of squid to enhance biodiversity.
- **Feeding Management**: Use commercial feeds with over 35% crude protein, or supplement with fish, silkworm pupae, snail meat, and animal by-products. Add plant-based feeds such as vegetables, grains, rice bran, and wheat bran. Feed once daily in the evening, placing food near the water’s edge or in shallow areas. Adjust the feeding amount based on previous consumption, typically 3–5% of the crabs’ body weight.
2. **Rice Field Crab Farming**:
- **Field Selection**: Choose fields with clean water, good irrigation, and strong water retention. Use rice varieties with strong resistance to pests and diseases, and narrow leaf angles for better growth.
- **Crab Stocking**: One month before stocking, remove silt and debris, then disinfect using lime and tea bran (150g lime and 50g tea bran per square meter). Apply lime first, followed by soaked tea bran the next day.
- **Feeding and Management**: Feed crabs immediately after they are introduced. Mix small fish, snail meat, bean cake, and wheat bran for balanced nutrition. Feed once daily in the evening, around 3% of their total weight. Maintain a water depth of at least 30 cm, increase it during hot weather, and change the water every 15–20 days. Regularly monitor the field for issues and implement anti-predator measures.
Third, important cultural precautions include:
- **Quality Seedlings**: Avoid cheap or unverified sources; high-quality seedlings are essential for healthy adult crabs.
- **Preventing Early Maturation**: This can reduce quality and yield. Control feed quantity, stocking density, and water temperature.
- **Water Quality Management**: Ensure clear, well-oxygenated water with suitable temperature. Plant aquatic vegetation and maintain a balanced diet.
- **Disease and Pest Prevention**: Regularly apply lime and avoid pesticides and fertilizers that could harm crabs. Natural predators like frogs, birds, and rodents must be controlled.
Fourth, effective escape prevention is critical. Use durable materials like fiberglass or calcium plastic panels for pond barriers. Avoid plastic films due to their weakness and tendency to age. Conduct daily inspections, check for leaks, and remove leftover food and dead crabs promptly.
Finally, harvesting should occur in mid-September, using methods like trapping, netting, or manual collection. Proper management ensures crabs reach 100–180 grams by autumn, with high catch rates and excellent economic returns. After harvest, store crabs in small enclosures or temporary boxes to maintain quality and maximize profit.
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