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Fry pond set of young cubs
The use of fry pools in pearl farming is an effective way to optimize water resource utilization, reduce operational costs, and improve breeding efficiency. These pools serve as a controlled environment for raising young fish, making it easier to manage their growth and health.
Before stocking, the fish ponds must be well-prepared. They should have sufficient water supply, good drainage systems, clean water quality, adequate sunlight, and easy access for transportation. The ideal size of the pond ranges from 1 to 5 acres. In winter, the ponds are renovated by removing excess silt, ensuring that the layer does not exceed 3 cm. In April, lime is applied at a rate of 75–100 kg per acre to disinfect the pond thoroughly. Three days before introducing the fry, water is filled to a depth of 33 cm. Five days prior to stocking, organic manure (150–200 kg per acre) is added to enrich the water. Before stocking, the pond is checked by pulling out the nets to remove any unwanted fish, pests, or insects. Fish screens are installed at the inlet and outlet to prevent larger fish from entering and preying on the young.
For stocking, it is recommended to raise species such as oysters, clams, grass carp, and silver carp. A total of 140,000 fry per mu is stocked, with the following distribution: 42% carp, 25% bighead carp, 23% grass carp, 5% silver carp, and 5% other species. Juvenile stocking typically occurs at the end of June or early July, with 10,000 fingerlings per mu, each measuring around 3 cm in length.
Feeding management plays a crucial role in the growth of the fry. During the early stage, soybean milk is used as the primary feed, while in the middle stage, rapeseed cake is introduced. In the later stages, organic manure becomes the main source of nutrition. Feeding is done twice daily—at 9–10 am and 4–5 pm. The fertilization strategy involves using small amounts of fertilizer to maintain water clarity and nutrient balance.
After about 10 days of rearing, the fry grow to approximately 1.3 cm in length. At this point, they are ready for further development. When the fry reach 2.5–3 cm, they are moved into larger nets in the morning when the fish do not float, ensuring they adapt well to the new environment.
To prevent predation, especially from leeches, 0.3 grams of crystallized trichlorfon is applied per cubic meter of water five to seven days after stocking. This helps control harmful organisms and ensures a safer environment for the growing fry. With proper management, these fry pools can significantly enhance productivity in pearl farming operations.