Detailed Explanation of Key Technical Points for Spring Broodstock Cultivation

After the beginning of spring, the water temperature gradually rises back up, especially during the pre-spawning stage from March to April, when fish activity intensifies, development accelerates, and food intake increases accordingly. This stage is an important period for gonadal development of broodstock. Practice has proven that the quality of spring broodstock cultivation is the key to the success or failure of artificial breeding of Chinese carp, therefore, the following points must be well implemented.

1. Feeding: Grass carp broodstock are mainly fed grass and concentrated feed. According to the availability of grass, generally grass is fed in the morning and concentrated feed in the afternoon, both of which should be fed at fixed feeding platforms. When green feed is scarce in early spring, grass carp can be fed some wheat, grain sprouts, lettuce, or green vegetable leaves. In the later stage, feed ryegrass, aquatic plants, etc. The feeding amount is 2%-4% of the fish body weight, with the criterion being that the feed is consumed within 2-3 hours. Broodstock must be fed a certain amount of animal feed, and live snails and clams should be fed once every 2-3 days. Silver carp and bighead carp broodstock are fed daily with powdered concentrated feed at 1%-2% of fish body weight. One month before induced spawning, if the water quality is relatively fertile, feeding can be stopped.

2. Fertilization: Silver carp and bighead carp broodstock ponds are generally mainly fertilized. Apply organic fertilizer once every 7-10 days, 100-150 kg per mu each time, using the broadcasting method. If organic fertilizer is insufficient, some chemical fertilizer can be applied appropriately, once every 5-7 days, about 5 kg each time. Fertilization should be moderate to prevent oxygen deficiency and pond turnover caused by excessive application. When fertilizing, flexibly adjust according to the degree of fertility of the pond water quality. The water of silver carp broodstock ponds is best when it is oil-green or yellow-green, while bighead carp broodstock ponds are best when tea-brown. Maintain transparency between 35-40 cm. Fertilization can be stopped half a month before induced spawning.

3. Regulating water quality: After the beginning of spring, because the pond has gone through a winter, the physical and chemical factors and plankton conditions in the water are not conducive to energy conversion. Therefore, before starting feeding and fertilization, it is best to replace half of the broodstock pond water and maintain a water depth of 1 m. Silver carp and bighead carp ponds should be flushed once every 20 days, adding water to a depth of 3-5 cm each time; grass carp broodstock ponds should be flushed once every 10-15 days, adding water to a depth of 5-10 cm each time. One month before induced spawning, flushing can be done once every 2-3 days. The water flow rate during flushing should not be too rapid, to prevent broodstock from excessively consuming physical strength by swimming against the current.

4. Pond inspection and disease prevention: Inspect the pond once each at dawn and dusk every day to check whether fish are gasping at the surface, whether food intake has increased or decreased, and whether the water is fertile or lean. Solve problems promptly when found. When the water temperature rises, disinfect the feeding area of broodstock ponds once every 10-15 days. Use about 0.5 kg of bleaching powder per pond, dissolve it in water, and splash it on the feeding area and its surroundings.