The Harm Caused by Algae and Its Management
2026-06-05
I. Preparations Before Stocking Fry
Select high-quality postlarvae: prioritize those with a strong reputation and robust stress resistance, and inspect the shrimp for a clean body surface, absence of deformities, and a well‑filled gut.
- Ensure that physicochemical water quality parameters remain within acceptable ranges: Prior to stocking, verify that key water quality parameters are optimal—maintaining a pH of 7.8–8.8 (with fluctuations of no more than 0.5 between morning and evening), ammonia nitrogen below 0.3 mg/L, nitrite below 0.2 mg/L, total alkalinity above 80 mg/L, and residual chlorine below 0.025 mg/L.
- The day before stocking postlarvae, a trial stocking must be conducted. Procedure: First, remove the nursery water from the hatchery‑raised shrimp postlarvae; then, transfer both pond water and the postlarvae into a trial‑stocking container. Observe for at least 24 hours; if no mortality is observed, the stock can be released. If mortality occurs, potential contributing factors may include pond pH, ammonia nitrogen, nitrite levels, or residual drug residues. Identify the underlying cause and implement appropriate corrective measures before proceeding with stocking.
(4) Properly manage temperature differences. Upon arrival of the shrimp postlarvae at the pond, immediately place the bags in the pond and let them soak for about 30 minutes to allow the bags to acclimate to the water temperature and equalize the internal water temperature. Release the postlarvae only when the water temperature inside the bags is essentially the same as that of the pond.
(5) Replenishing Microorganisms and Cultivating Algae
Three days before stocking the fry, please supplement with probiotics and cultivate algae in advance. “Diatom King (60 mu/bag) + Probiotic Complex (5 mu/package)” It can rapidly form bioflocs, increase the proportion of beneficial bacteria at the pond bottom, inhibit the proliferation of harmful bacteria, decompose organic matter at the bottom, and mitigate water eutrophication.
II. Precautions for Stocking Fry
① Stocking should be scheduled for after 9:00 a.m. on a sunny day or in the evening; avoid stocking during rainy weather or at noon under intense sunlight. One hour before stocking, apply Stress‑Relief and Detoxifier (3 mu per packet) by spraying it at the stocking site to enhance the shrimp postlarvae’s stress resistance, minimize their stress response upon entering the water, and reduce the duration of swimming erratically.
② Each shrimp pond should be stocked with the full recommended number of postlarvae in a single stocking.
③ Shrimp postlarvae should be released upwind, and the entire bag of postlarvae should first be immersed in the pond for half an hour, releasing them only when the water temperature inside the bag is roughly equal to that of the pond.
④ Stocking temperature: The optimal growth temperature for Pacific white shrimp is 28–32°C, with a survival range of 9–47°C; they cease feeding at 15°C and begin to die at 8°C. Generally, stocking can be carried out when the water temperature reaches above 18°C.
- Post-Stocking Procedures
On the day after stocking, apply polysaccharide‑activated ionic calcium (50 mu per bag) by broadcasting it across the entire pond to strengthen fish health and immunity, thereby improving survival rates.
After stocking the fry, closely monitor changes in pond water quality and conduct regular water-quality tests. Based on water conditions, carry out timely water exchanges, aeration, and water-conditioning measures; periodically apply microbial preparations such as Bacillus-based products to stabilize and maintain consistent water quality.
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