In recent years, South American white shrimp farming has been gaining momentum in Fangchenggang City. However, with the aging of shrimp ponds over time, a significant accumulation of organic matter—such as manure and leftover feed—has led to severe eutrophication at the pond bottom, along with a high concentration of pathogenic organisms. Traditional breeding practices have further exacerbated these issues. The repeated use of lime and bleaching powder has caused the pond bottom to become heavily calcified, reducing its buffering capacity and self-purification ability. After calcification, the pond water tends to lack phosphate and soluble silicate, making it difficult to apply fertilizers effectively and leading to unstable water quality. To address these challenges, we have summarized several aquaculture techniques aimed at improving production efficiency and sustainability.
**First, Preparatory Work**
1. **Improving Aging Shrimp Ponds**: One of the most effective ways to boost yield and breeding success is by upgrading pond conditions. This includes installing aerators, separating the water inlet and outlet, increasing sewage facilities, and raising the slope height to increase water depth.
2. **Clearing the Pond**: After harvesting, it's crucial to drain the pond, remove silt manually or mechanically, and expose the bottom until cracks form. High-concentration disinfectants should be sprayed on the subsoil, followed by plowing with a tractor or cattle to break up the soil. Then, compact the bottom to ensure a solid base for future farming.
3. **Fertilizing the Pond**: Fertilization can easily lead to algae growth, so special attention is needed. About 10 days before stocking, seawater is filtered to around 1 meter, and quaternary ammonium salt complexed iodine disinfectant (1–1.5 mg/L) is applied. Two to three days later, photosynthetic bacteria (10–15 mg/L) are added. Aeration is then used to make the water cloudy. If the water color doesn’t develop, seawater auxin or phosphates/silicates may be added. Typically, 1.5 kg urea and 1 kg superphosphate per pond are recommended.
**Second, Shrimp Selection and Stocking Density**
1. **Selecting Healthy Seedlings**: Healthy, disease-free seedlings are essential for successful breeding. Criteria include size (0.8–1.2 cm), strong vitality, consistent body color, full gastrointestinal tract, and no physical damage.
2. **Acclimating Seedlings**: Seedlings are sensitive to temperature and salinity changes. Before release, they must be acclimated gradually. Seedlings should be introduced early morning or late afternoon, and the plastic bags should be floated in the pond for 20 minutes to balance temperatures. A small test with a few seedlings in a bucket of pond water helps confirm survival rates (should be above 95%).
3. **Stocking Density**: Stocking density should be determined based on pond conditions. In aging ponds, 20,000–30,000 shrimp per mu is generally recommended to ensure manageable growth and easier monitoring.
**Third, Water Quality Management**
1. **Using Beneficial Microorganisms**: Regular application of beneficial microbes like photosynthetic bacteria and probiotics helps break down organic waste, reduce harmful substances, and promote algae growth, which in turn supports natural food sources for shrimp.
2. **Water Exchange**: Early stages require minimal water changes, while mid-stages involve exchanging 20% of the water every 10–14 days. Later stages need more frequent exchanges (every 7 days, 80–100 cm deep). Continuous water exchange and biological agents like photosynthetic bacteria help maintain stable water quality.
3. **Aerator Use**: For every 0.25 hectares, two waterwheel aerators, one submerged tube, and one jet flow system are recommended. Aeration is especially important during low-oxygen periods, such as cloudy or rainy days, to keep dissolved oxygen levels above 5 mg/L.
4. **Monitoring Environmental Factors**: Regular testing of pH, temperature, ammonia, and nitrite levels is essential. Sudden changes indicate potential ecological imbalances, requiring immediate action to stabilize the environment.
**Fourth, Feed Selection and Feeding Practices**
1. **Choosing High-Quality Feed**: The quality of feed directly impacts shrimp growth, survival, and disease resistance. Selecting nutrient-rich, stable brands is key.
2. **Feeding Strategy**: Feeding amounts should be adjusted based on shrimp size, water temperature, and weather. Overfeeding leads to pollution, while underfeeding affects growth. Juvenile shrimp are fed 2–3 times daily, with evening feeds accounting for 50–60% of the total. Vitamins and immune boosters can also be added to improve disease resistance.
**Fifth, Drug Use**
Ponds should avoid unnecessary drug use. Prevention is better than cure, and when necessary, only approved, safe drugs should be used. Proper dosage and timing are critical to avoid misuse and long-term environmental damage.
These measures aim to enhance productivity, ensure sustainable practices, and support the development of the shrimp farming industry in Fangchenggang.
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