Broodstock selection is a critical first step in successful fish breeding. The broodstock must be purebred to ensure genetic quality. They should be strong, healthy, and free from disease or severe injuries. The sex ratio should be balanced, typically 1:1 for males and females. Female broodstock should be at least 3–4 years old and weigh over 1.5 kg, while males and females should be at least 2–3 years old and weigh more than 1 kg. It's best to prepare broodstock a year in advance of the spawning season rather than collecting them on short notice during the breeding period. Keeping them in well-maintained ponds ensures better results.
In terms of broodstock management, the development of gonads and egg production are closely related to the quality and variety of feed provided. A diverse diet that includes both plant-based and animal-based foods is essential to meet the nutritional needs of the broodstock, especially for essential amino acids. Avoid feeding them a single type of food for extended periods.
The maturation of the broodstock’s gonads also depends on a suitable ecological environment. Throughout the breeding process, maintaining good water quality is crucial, with adequate oxygen levels. In autumn, pond water often becomes stagnant, so regular water changes and the maintenance of plankton populations help keep the environment comfortable. This promotes fat accumulation, which is vital for successful egg production.
It's important to focus on broodstock preparation from the previous year. By winter, the eggs have completed their growth phase, and in spring, only a small amount of supplementary feed is needed to restore the broodstock’s health. If they were not properly prepared the previous year, their gonads may be underdeveloped, leading to poor reproduction success.
For spawning, the pond should be between 0.2 and 1 mu in size, with a depth of about 1 meter. The bottom should be clean, with easy access for water inflow and outflow. The area should be quiet and well-lit. Before use, the pond must be disinfected, and the incoming water should be filtered.
Fish nests can be made from palm leaves, aquatic plants, grass, or synthetic fibers. They should be spread evenly once filled with water, ensuring they are secure and easy to manage. Disinfection is necessary before use. Place the nests in shallow water, about 1 meter from the shore, using either suspended or flat column arrangements. Flat columns are most effective.
Nest management involves timing the spawning correctly and replacing nests promptly—usually one hour after spawning. Too many nests can reduce effectiveness, so 4–5 per female is ideal.
To stimulate spawning, oxytocin injections (types I or II) can be used. For females, administer 0.5 ml/kg, and for males, 1/3 to 1/4 of that dose.
Incubation can take place in earthen or concrete ponds. Earthen ponds are 0.5–1 mu with 1-meter depth, while concrete ponds are 20–50 square meters with 50–80 cm depth. Egg density is usually 3,000–5,000 per cubic meter.
Wet hatching involves placing the fish nests in an indoor or plastic structure, keeping them moist by spraying water. Maintain a temperature of 20–25°C, regularly mist the nests, and avoid drying. Keep humidity high and monitor hatching time carefully.
Dry hatching involves removing the sticky coating from fertilized eggs using methods like mud, talcum powder, or water treatment. This helps prevent fungal infections and improves hatching success.
When fry emerge and the yolk sac disappears, begin feeding immediately. Maintain water quality by regularly changing water, but ensure the temperature difference does not exceed 3°C. Avoid adding water while feeding to prevent fish from eating the surface.
During hot weather, watch for bubble disease and change water frequently. Remove frogs, dragonflies, and other aquatic pests to protect the fry.
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