(1) Broodstock Breeding. Broodstock should be raised in a dedicated pond, typically 1-2 mu in size with a depth of 1.5 to 2 meters. The water source must be clean, and the pond should have good drainage and irrigation systems. A muddy bottom with aquatic plants is ideal for their growth. Daily feeding with an appropriate amount of bait fish is essential. Two months before breeding, male and female fish should be kept in separate ponds. In some lakes or reservoirs where squid populations are abundant, adult fish caught in spring can also serve as broodstock. Select individuals weighing over 0.5 kg for males and 1–3 kg for females, ensuring they are not injured during capture.
(2) Sex Identification. Female fish have a rounded lower jaw that slightly protrudes beyond the upper jaw, and their genital pore appears as a "one" shape, surrounded by pink tissue, located between the anus and urinary opening. Male fish have a pointed lower jaw that extends well beyond the upper jaw. Their genital and urinary openings merge into a single small hole behind the anus. When sexually mature, the female’s abdomen becomes swollen, soft, and elastic, with visible ovarian contours. The midline of the belly is concave, and the genital pore is swollen and open. When gently pressed, male fish release milky white sperm.
(3) Oxytocin Induction and Hatching. A mixture of salmon pituitary (PG), chorionic gonadotropin (HCG), and a luteinizing hormone-releasing hormone analog (LRH-A) is commonly used. Dosages include: 1 mg PG + 5.2 mg HCG per 1000 IU, or 10 mg PG + 300 µg LRH-A. Injection is administered at the base of the pectoral fin, usually once or twice. The effect lasts 6–12 hours longer than in other fish. Fertilization methods depend on production scale and broodstock availability. Natural spawning causes less stress and is ideal for large-scale breeding, while artificial insemination is more damaging but suitable for small-scale operations. Combining both methods is also possible. After natural spawning, broodstock that haven't released eggs can be artificially inseminated. Squid have sharp, hard rays, so when handling, pinch the mandible with thumb and forefinger, lift the fish, and wrap it in gauze to avoid injury. Fertilized eggs hatch directly in a circular tank. Due to their slight viscosity and semi-floating nature, they sink in still water. Water flow should be maintained at over 20 cm/sec to prevent sinking. If no circular tank is available, running water hatching tanks can be used. Water quality must be fresh, with adequate dissolved oxygen and no pollution. Maintain a temperature of 23–29°C for optimal development. The fertilized eggs develop slower than those of domestic fish, taking about 30 hours to hatch at 25–30°C.
(4) Seed Cultivation. Carp fry cultivation can take place in seedling ponds or cages, but requires careful management. Seedling ponds are generally 0.1–0.2 mu in size, 1.5 m deep, with clean water, good drainage, and minimal silt. Most farms now use hatchery rings or cages placed in pools for easier management. Cages are set in micro-flow basins, and both the cage and fish are sterilized before stocking. The "opening period," from fry emergence to fin development, takes about 3 days. During this time, feed with 24–72-hour-old salmon trout or 24–60-hour-old grass carp fry. Carps begin feeding 1–2 days after oxytocin treatment. The density of live bait should be 15 times that of the fry to encourage feeding. From the opening stage to reaching 3.3 cm, it takes about 12–18 days. At this stage, ensuring sufficient and nutritious live food, along with regular disinfection and disease prevention, is crucial. Common diseases include saprophytic infections, worms, and small melon worms, which thrive in 20–30°C water and can cause high mortality. Prevention includes sterilizing live bait in 3% saline for 10–20 minutes and treating fry in formalin solution. For treatment, apply a 0.7 g/m³ mixture of copper sulfate and ferrous sulfate (5:2) 2–3 times daily, followed by a 2% formalin dip. Small echinococcosis can be treated with 2 g/m³ mercuric nitrate or 0.1 g/m³ quinaldine. Rickets can be managed with 0.2–0.5 g/m³ trichlorfon or 1.5 g/m³ potassium permanganate bath. Once fry reach 3.3 cm, they become more robust and resemble adult fish, with improved feeding ability. Live feed must be provided in various sizes according to their growth stage. If further rearing is needed, they can be kept in cages, cement pools, or small earthen ponds. Stocking density in flowing water is 200–500 fish per cubic meter, and 100 fish per cubic meter in static pools. Use live fish, wild fish, or shrimp as bait.
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