Autumn is a critical period for the outbreak of "black spot" and "red spot disease" in farmed green shrimp. Both juvenile and adult shrimps are susceptible, which can significantly impact the efficiency and profitability of shrimp farming. It's essential to implement effective preventive measures to reduce losses.
**Black Spot Disease**
This disease commonly occurs in high-density shrimp ponds and is primarily caused by poor water and sediment quality. The accumulation of organic matter leads to an overgrowth of chitin-decomposing bacteria, resulting in rapid infection, high mortality, and serious damage to the shrimp population. At the early stage, small gray or brown spots appear on the shrimp’s body, gradually spreading to the abdomen, appendages, and even the carapace. In severe cases, the spots become depressed with ulcers, leading to direct damage to the internal tissues. Affected shrimps show reduced activity, loss of appetite, and often float near the surface or remain in shallow areas until they die.
To prevent black spot disease, especially during summer and early autumn, the following measures should be taken:
1. Regularly add fresh water to maintain good water quality. In areas with limited water exchange, apply quicklime (25 mg/m³) or water quality enhancers once or twice a month to improve conditions.
2. Feed high-quality, clean feed in a regular, fixed, and controlled manner to avoid leftover food that pollutes the water. Handle equipment gently to minimize physical injuries.
3. Reduce stocking density, particularly in high-density ponds, keeping it below 80,000 per mu to ensure better living conditions.
4. If the disease appears, treat the entire pond with 1 mg/L nitrofurazone or 25 μg/L formalin. After 12 hours, replace the water daily, repeating this 2–3 times depending on the situation.
5. For large-scale outbreaks, add 0.3% of sulfonamides such as sulfadiazine or iodothiazole to the feed and continue feeding for 5–7 days alongside the treatment.
**Red Spot Disease**
Although not as sudden or widespread as black spot, red spot disease causes persistent and recurring deaths. Initially, small red spots may appear on the shrimp’s appendages, carapace, or tail. Over time, these spots increase in number and intensity. In severe cases, one side of the shrimp becomes dark, and the affected shrimp may stop moving within 2–4 days, eventually dying in shallow waters. Shrimp that survive the disease often have poor meat quality, making them difficult to sell at a good price.
Prevention strategies for red spot disease include:
1. Maintain clear water in late summer and early autumn, ensuring a transparency of at least 40 cm and keeping half of the pond area covered with water.
2. Apply quicklime (25 mg/m³) or water quality improvers monthly and adjust stocking density appropriately.
3. Treat affected ponds by adding 1 kg of norfloxacin per kg of feed and feed continuously for 7 days without other feed.
4. After using norfloxacin, combine it with 0.8 mg/L “Strong Chloride,†preferably applied on sunny days across the entire pond to effectively control the spread of the disease.
By implementing these proactive measures, farmers can significantly reduce the risk of disease outbreaks and ensure healthier, more profitable shrimp production.
Spicy Taste Dried Alaska Pollack
Russian Dried Fish Snack,Pollock Alaska Fish Delicious,Seasoned Dried Fish Delicious
yanbian zhenxiang foods , https://www.driedpollock.com