Macrobrachium rosenbergii large area breeding technology

Ponds are carefully selected based on several key factors, including a reliable water source, flat and stable bottoms, ease of irrigation and drainage, fresh water quality, and good seepage resistance. Most pond bottoms consist of semi-lime sandy soil, while some are constructed on previously unused or marginal lands. The majority of ponds are traditional freshwater fish ponds, typically located at river mouths with salinity levels below 5‰. The average pond size ranges from 0.33 to 0.67 hectares, with a length-to-width ratio of 2:1 to 4:1, oriented east-west for optimal sunlight exposure. The depth of the pond is usually maintained between 1 and 1.2 meters. Before stocking, excessive silt is removed, and the pond is disinfected using quicklime. This process helps increase calcium content in the water, improving overall water quality. Disinfection can be done either dry or wet. Dry disinfection is typically carried out about half a month before releasing seedlings. It is performed on a sunny day, with the pond bottom kept at a water level of around 10 cm. Approximately 100 kg of lime is used per 667 square meters. For wet disinfection, 200 grams of lime is added per cubic meter of water. After disinfection, an 80-mesh grate net is installed at the inlet to prevent wild fish and eggs from entering. About 5-8 days before stocking, the water level is raised to 50-70 cm. To enrich the pond’s natural food supply, base fertilizer and water are applied before stocking shrimp. Freshly dug ponds receive 250-400 kg of fermented organic manure per 667 square meters, while older ponds use half that amount. Aquatic plants are also planted in shallow areas of the pond, covering no more than 20% of the total area. Alternatively, structures like tree branches, old nets, or tiles are placed to provide hiding spots and reduce aggression among the shrimp. Stocking of *Macrobrachium rosenbergii* begins in late May to early June when the water temperature stabilizes above 18°C. Each 667 square meters receives approximately 8,000 seedlings of about 1.5 cm in size. Prior to this, 10–30 tails per kilogram of larvae and small crustaceans are introduced to provide additional food sources. Feeding is conducted following the "four principles" – timing, location, quality, and quantity. The daily feeding rate is 3–6% of the shrimp’s body weight, divided into three feedings at 9:00, 15:00, and 19:00. Freshwater is added every 3–4 days to maintain water clarity and keep the transparency between 30–40 cm. During periods of sudden water rise in early spring or after rain, part of the water is drained to maintain a depth of 0.7–1 meter. Water color is monitored closely, with greenish hues like grass green or oil green being ideal. If the transparency exceeds 40 cm, fertilization is applied to maintain a balanced and healthy environment. Special attention is given to monitoring during the late afternoon and early evening, especially during high-temperature periods. Shrimp activity, feeding behavior, and signs of stress such as floating heads are observed regularly. Any abnormal conditions, such as frog eggs, leftover bait, or debris, are promptly removed. During hot weather, lime is applied every 20–30 days at a rate of 15–20 kg per 667 square meters. Bleach powder is also used at 0.5–1 g/m³ every 30 days to prevent disease outbreaks. If any illness is detected, immediate treatment is necessary. Harvesting should occur when the water temperature drops below 18°C to ensure optimal growth and quality.

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