Artificial breeding of fry begins with selecting broodstock. Choose fish that are in their 3rd to 5th instar stage, weighing between 2.5kg and 3.5kg. During non-breeding periods, males and females can be distinguished by slight differences in head shape and body color—males tend to have slightly broader heads and darker bodies, while females have narrower heads. In the breeding season, males develop larger muscle tumors on either side of their heads, and both sexes show visible gonads. Females have a round, concave genital opening and a soft, swollen abdomen, whereas males have a harder, stiffer belly. The male-to-female ratio should be maintained at 3:2 for optimal breeding success.
The broodstock are raised in ponds covering approximately 2,500 square meters, with a water depth of around 1.5 meters. Stocking density is about 20 to 30 per 667 square meters. When the water temperature exceeds 13°C, special feed is introduced. At temperatures above 21°C, the feeding rate is set between 2% and 4%, with additional supplements such as boiled small fish, shrimp, and plant-based feeds like malt. Every 10 days, the broodstock are rinsed to stimulate gonad development.
For artificial hormone stimulation, common agents include carp pituitary (PG), human chorionic gonadotropin (hCG), and luteinizing hormone-releasing hormone analogs (LRH-a). Female fish receive PG at 4–6 mg/kg, hCG at 1,000 IU/kg, or LRH-a at 2–2.5 mg/kg. Males receive half the dose. These hormones help accelerate the spawning process.
To encourage spawning, artificial nests made from plastic buckets, iron containers, or wooden boxes are placed in the pond. One end remains open for fish to enter, while the other is covered with nylon cloth. After spawning, the nests are positioned at the bottom of the pond, 3–5 meters deep, with the opening facing the center. A float is attached for easy retrieval. Nests are spaced 9–10 meters apart and make up about 50% of the broodstock population.
When the water temperature is above 21°C, the nests are checked daily between 10 am and 11 am. If eggs are present, they are carefully removed and placed into smooth barrels filled with water. This helps protect the eggs during early development.
Fertilized eggs hatch within 110–120 hours when the water temperature is between 25°C and 29°C. It takes about 10 days for larvae to develop into juveniles. Eggs can be naturally hatched in ponds or in hatching tanks. Optimal incubation conditions include a water temperature of 25–28°C, pH between 6.5 and 8.0, and dissolved oxygen levels of at least 6 mg/L. Water exchange should be around 20 liters per minute.
To prevent fungal infections, treatments such as formalin or mildewin can be alternated. Before the eggs turn red, they are immersed in water mold net at 60–65 mg/L for 10–12 minutes, or in formalin at 100 mg/L for 4–10 minutes. This helps reduce the risk of saprophytic infections.
In summer, fish breeding involves preparing suitable nursery ponds. Seedling pools should be near a water source, with good water quality, convenient water intake and drainage, a flat bottom, and minimal silt. The summer flower nursery pond is typically around 667 square meters, while the breeding pond ranges from 2,001 to 3,335 square meters with a depth of 1.3–1.6 meters. Each pond should have an aerator of 1.5 kW or 2.5 kW and a pump for water circulation.
Before stocking, the pond is drained, cleaned, and left to dry for 20 days. Lime is then applied at 75–100 kg per 667 square meters to disinfect the area. Ten days before stocking, the water is filtered and raised to 0.6–1 meter in depth. Fermented organic manure, such as animal dung or cake fertilizer, is added at 100–500 kg per 667 square meters to promote natural plankton growth.
After 3–4 days, fry grow to 4–5 cm in length. This method is similar to traditional "Four Homes" fry cultivation, with 30,000–50,000 fry per 667 square meters. After 20–30 days, they are moved to larger ponds for further growth. Summer flowers are cultivated to reach about 50g, with 8,000–9,000 fish per 667 square meters. Squid and other species are also stocked at 6–10 cm in size.
Once stocked, the fish are fed for 4–5 days with zooplankton before transitioning to compound feed. Feeding is done by creating sound cues to attract the fish, followed by gradual bait distribution every 10 seconds. This taming process lasts 10–20 minutes, repeated over 4–7 days to establish feeding habits. Feed should contain about 40% protein, and it is given twice daily at a rate of 3–5%.
Daily management requires maintaining dissolved oxygen above 3 mg/L and a pH between 6.5 and 8.3. Water is exchanged every 7–10 days, gradually increasing the depth to 1.5 meters. Chlorine dioxide is used periodically at 0.5 mg/L to prevent disease and maintain water quality.
For seed fishing and transportation, summer flowers are usually caught in the morning or evening when the water is cooler. For air transport, they can be caught the day before and kept in seedling boxes overnight. Transport is done using 30cm x 30cm x 40cm nylon bags filled with 3–4 liters of water, holding 1,500–3,000 fish per bag. They can be transported for 12–18 hours. To prevent damage, bags are packed in cardboard boxes and secured with rope.
Fish fingerlings are caught from November to April, during warm, sunny weather. Two net exercises are performed before capture, followed by a 2-day rest and 3-hour water flush. For transport, oxygenated nylon bags are used, with each bag containing no more than 0.5kg of fish. Fish oysters are preferred for transport, with smooth interiors and nylon lining to avoid abrasion. Pure oxygen is supplied, and the density is about 30kg per cubic meter of water.
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