Pond Conditions
The pond area ranges from 0.2 to 0.33 hectares, with a water depth of 1 to 1.2 meters. The water source is abundant, and the water quality is excellent, making it easy to manage both irrigation and drainage. The pond structure is stable, with no leakage issues, and the bottom is flat and free from excessive silt buildup. These conditions are ideal for raising fish fry, as they ensure a clean and controlled environment for early development.
2. Pond Cleaning and Disinfection
Before starting the breeding process, the pond is left with 10 to 20 centimeters of water. Approximately 80 grams of lime per 667 square meters is used to disinfect the pond. Once the lime is dissolved, hot lime water is evenly poured into the pond. The following day, the pond mud is turned using a shovel to mix the lime slurry with the silt. This process helps eliminate wild fish and harmful organisms while encouraging dormant plankton eggs in the mud to hatch and become active.
3. Water Filling and Fertilization
Three days after disinfection, water is introduced into the pond to a depth of about 70 cm. The water inlet must be covered with a 40-mesh net to prevent predators from entering. Afterward, 150 kg of fermented manure or 50 kg of soybean milk is added per 667 square meters to enrich the water with nutrients. This ensures that the pond has sufficient plankton, which serves as a natural food source for the fry.
4. Fry Holding and Transportation
Fry can be transported using oxygenated bags to maintain good water quality during transit. Before transportation, the fry should be kept in a holding cage for 5 to 6 hours to help them adapt and reduce waste accumulation. It's best to use well water for transport, but if unavailable, low-organic-content water can be used instead. In high-temperature conditions, ice can be added to keep the water cool during the journey.
5. Fish Fry Stocking
To ensure the fry have enough natural bait such as rotifers and small copepods, stocking usually begins 8 to 10 days after pond cleaning, when these microorganisms are at their peak. When releasing the fry, it's important to match the temperature between the transport water and the pond water, ensuring the difference does not exceed 5°C. The best time for stocking is on a sunny morning, with a recommended density of 40,000 to 50,000 fry per 667 square meters for fry measuring 0.8 to 1 cm in length.
6. Daily Management
Throughout the fry-rearing process, the availability of natural food is crucial. The pond needs to maintain an adequate supply of palatable feed at all developmental stages. Regular checks of the food biomass are conducted every morning and evening. After 3 to 5 days of feeding, the biomass may decrease, so organic fertilizer should be added every two days, approximately 10 to 15 kg per 667 square meters. Alternatively, plankton from other ponds can be used as supplementary feed. Water levels should also be increased by 10 to 20 cm every other week to maintain good water quality. After 12 to 15 days, the fry should reach a length of 3 cm or more, with a survival rate of 80% to 90%.
7. Disease Prevention and Treatment
Stingrays are generally resistant to diseases, especially when water quality is well maintained. Routine disinfection is rarely necessary. However, if treatment is required, only approved medications that are highly effective, low in toxicity, and have minimal side effects should be used. Since stingrays lack scales, they are sensitive to certain chemicals like trichlorfon and copper sulfate. Therefore, these substances should be avoided to protect the health of the fry.
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