Shrimp and crabs can be farmed together, but the system must be carefully designed. When properly managed, mixed culture can bring mutual benefits to both species. However, an improper model may lead to negative outcomes, where losses outweigh gains. After years of research and field trials, we have found that two specific models—“shrimp-crab-shrimp†and “crab-shrimpâ€â€”are effective, while other polyculture methods are less suitable.
The first model is the “shrimp-crab-shrimp†approach. In the first year, large shrimp are stocked in winter and raised until May of the following year. After they are harvested, crabs are introduced and raised until October, when they are ready for harvest. Then, young shrimp are restocked for the next cycle. Here’s how it works:
1. In newly opened ponds or those not requiring drying in winter, 5–10 kg of large shrimp can be released in late October, growing until May of the next year. These shrimp can yield about 10–30 kg per mu, generating around 1,000 yuan in profit. The key is continuous feeding throughout winter, except during ice periods. In spring, especially April, feeding should be intensified. Harvesting starts with traps, and finally, the pond is dried out, which helps in cleaning and preparing for crab farming.
2. In mid-May, juvenile crabs and small shrimp are kept in cages or small ponds for better management and higher survival rates. Typically, this increases survival by 5% to 10%. After about 20 days, the crabs are moved into the main pond. During crab growth, maintaining a good ecological environment is crucial—adequate aquatic plants, clean water, and proper stocking density. Based on trials over 400–3750 mu, it's recommended to stock 1000–1500 crabs per mu. This can yield about 40 kg of crabs per mu, bringing in roughly 2,500 yuan. Too few crabs result in low yields, while too many may reduce size and market value.
3. By late June to early July, 1–2 kg of egg-bearing shrimp are introduced per mu. By October, after crabs are harvested, these shrimp grow to 2–4 cm. At year-end, about 25 kg of shrimp can be harvested, with 15 kg of high-quality shrimp yielding around 1,500 yuan per mu. This model can generate up to 5,000 yuan per mu annually.
The second model is the “crab-shrimp†approach. Winter and spring require pond cleaning and disinfection before March. Fertilizers and aquatic plants are added in mid-April, followed by crab stocking in early May. By late June, egg-bearing shrimp are introduced. Crabs are managed as usual, while shrimp are harvested using a combination of trapping methods. Shrimp are fed continuously without lowering the water level. Before and after the Spring Festival, when shrimp prices drop, trawl nets can be used to catch 30–40 kg of shrimp per mu. This system offers strong economic returns.
Both shrimp and crabs are benthic species with similar feeding habits. However, during the peak growth period of crabs (June to September), too many shrimp can compete for oxygen and space, affecting crab size and yield. It's not advisable to introduce shrimp seedlings in spring, as they may grow too quickly and compete with crabs, reducing their quality and market value. Additionally, multiple breeding cycles can lead to overcrowding, making it hard to achieve large shrimp sizes.
In both models, adding a small number of compatible fish species can further boost economic returns without negatively impacting shrimp or crab production.
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