In the middle and later stages of shrimp farming, once the shrimp reach a body length of 7–8 cm, significant changes in water quality and bottom conditions begin to occur. This is primarily due to increased feeding, accumulation of shrimp waste, dying algae, leftover feed, and organic decomposition at the pond bottom. These factors lead to dramatic shifts in water clarity, microbial balance, and overall pond health.
The environmental changes during this period are quite noticeable. The pH level tends to rise, the water color transitions from greenish-yellow to brown or tea-green, and the water becomes more turbid with reduced transparency. The pond bottom often turns dark and emits a strong odor. Harmful microorganisms multiply, and shrimp may show signs such as red tails and tentacles, even with tail damage. Some ponds experience slow growth, weak physical condition, poor responsiveness, lack of molting, and ciliate infestations. Shrimp may also suffer from enteritis, jaundice, and display symptoms like floating heads, soft shells, red legs, eye rot, and shell ulcers.
Based on years of shrimp farming experience, the following management strategies have been developed for the middle and later stages of aquaculture:
First, stabilizing the water and reducing turbidity is essential. A lack of magnesium ions can cause algae to die off, leading to color changes. To address this, dolomite (20–25 ppm) is applied every 7–10 days to stabilize the water color. To reduce turbidity, photosynthetic bacteria (10–15 ppm) are used weekly. Regular disinfection is also important—using dibutyl hydantoin at therapeutic concentration in the morning, followed by organic iodine and quaternary ammonium salts the next day. Adjustments can be made depending on the situation.
Next, balancing nutrients in the water is crucial. Calcium, magnesium, and phosphorus levels should be maintained. Dicalcium phosphate (2–3 ppm) is added every 10–15 days, along with dolomite powder (20 ppm). This helps maintain a stable aquatic environment.
Improving the sediment quality and controlling pH is also key. Beneficial microbial preparations (0.3 ppm) can be sprinkled every 10–15 days, while a bottom quality improver containing zeolite (10–15 ppm) is applied every five days. If heavy rain or cloudy weather causes a drop in pH below 7.5, lime (5–8 kg per 667 square meters) should be scattered throughout the pond to restore balance.
Water exchange should be done gradually. On the first day, change about 10 cm of water, then increase to 20 cm, 30 cm, and finally 50 cm over the next few days. This promotes better water quality and supports healthy shrimp growth. Ensure the water level is maintained and consider investing in oxygen-augmenting equipment to support larger-scale production.
Feeding should be done in a controlled manner. Feed four times daily, with the first feeding occurring 1–2 hours after sunrise when dissolved oxygen levels are high. The second feeding occurs after 6 hours, and the amount should be enough for shrimp to consume within 45 minutes to an hour.
To boost shrimp immunity and stress resistance, add immune polysaccharides (0.1%), biological enzyme additives (0.2%), vitamin C (0.1–0.2%), and vitamin B (0.05%) to the feed. This should be done for two consecutive days each week, with two meals per day. Garlicin (0.05–0.1%) can also be included.
Regular monitoring of shrimp health is vital. If shrimp eat less or float on the surface, it may indicate disease. At this point, immediate action is needed. During the middle and later stages, it's recommended to randomly sample 200–300 shrimp every 3–5 days using a fine-mesh net. If there’s a sudden change in feed consumption, or if weather conditions like heavy rain or wind change rapidly, or if disease risk increases after water changes, use a rotary screen to collect samples promptly.
By following these practices, farmers can maintain healthier shrimp populations, improve productivity, and achieve better economic returns.
Squid Rings Raw,Frozen squid rings,This year's Squid Rings
ZHOUSHAN JING YUAN FOOD CO.,LTD , https://www.genho-food.com