First, fry raising and cultivation
The fry are initially raised in a hatchery (cylinder) for 4 to 5 days. After 2 to 3 days of being released from the membrane, they can start feeding on rotifers. At this stage, it's important to use a sieve with 180-200 mesh size to feed them. The feeding density should be around 10-15 per milliliter, which is roughly equivalent to 1 to 2 drops of water. This ensures that the fry get enough nutrition without overfeeding.
After the initial rearing period, the fish are transferred to a culture pond for about 20 days, during which they grow to lengths of 2 to 2.5 cm. The Wuzi Cultivating Pool typically uses a cement pool with a smooth bottom, inlet, and outlet. A 40-60 mesh screen is placed at the water outlet to prevent fish from escaping. Once the fry are siphoned into a fine-mesh cage, they are counted, and any debris is removed. About 10,000 to 20,000 fry are stocked per cubic meter of water. They are fed once in the morning and once in the evening. Initially, they are given live rotifers, but as they grow, larvae and copepods are introduced. Feeding is done through a 100-120 mesh sieve, and the feeding density is gradually reduced. Daily management includes providing shade or hiding structures, maintaining a slight water flow or aeration to ensure dissolved oxygen levels remain above 4 mg/L. Water is changed by 25% to 30% daily, the water temperature must not exceed 30°C, and all feed should be rinsed with clear water before being added.
Second, fish breeding
The breeding pond should be between 2000 to 3000 square meters with a depth of about 1.8 meters, minimal silt, and good access to water and electricity. One week before stocking, the pond is cleaned, filled with water, and fertilized to cultivate natural food organisms. Plants, nets, straw, and other hiding objects are placed around the pond. When the food organisms reach their peak and the water quality stabilizes, the fry are introduced, placing them in the hidden areas. The main breeding area usually holds about 20,000 larvae per acre, with approximately 2000 carp stocked alongside. For rearing, 800 to 10,000 larvae per acre are stocked, and polyculture with squid, head lice, and other species can also be practiced, though only in small quantities. Polyculture species should only be introduced after yellow snapper have been successfully acclimated.
After 2 to 3 days of acclimation and initial feeding in the lower pond, a small amount of feed is placed within 5 to 6 meters on both sides of the feeding table, twice a day. A consistent sound is used to signal feeding, gradually narrowing the feeding area until it’s fixed at the feeding table. Successful domestication usually takes about 10 days. Two common types of feed are used: one is animal-based feed, such as frozen sea fish or poultry organs, mixed with flour, bran, and vitamins using a pelleting machine to create soft pellets; the second is commercial floating pellets, adjusted in size and protein content depending on the fish’s growth stage. Early-stage feed has a protein content of 40–45% and a particle size of about 1.5 mm, while later-stage feed has 35–40% protein and larger particles. Seedlings are fed 3 to 4 times a day. Stingrays prefer to feed in the evening and at night, so proper feeding practices are essential, especially when using a feeding machine. Each feeding session should last at least 20 minutes, with 80–90% of the fish eating.
Daily management of cultured stingrays involves keeping the water fresh, maintaining a transparency of over 40 cm, and frequently adding new water, preferably well water. Carp seedlings are sometimes added to help control algae. No fertilization is used during the cultivation process, and overfeeding must be avoided. Feeding is done at noon and at night, with aerators activated as needed. The water temperature should not exceed 30°C. Regular patrols of the pond are necessary to detect and address issues promptly.
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