Spring is a critical period for the growth and development of fish gonads. The quality of broodstock management during this season directly affects the success of artificial breeding of the four major carp species. Therefore, special attention must be given to spring cultivation practices.
First, the conditions of the broodstock ponds should be carefully considered. The ponds should be located near a water source to facilitate drainage, irrigation, and easy water quality control. For breeding eels and alburnus, it's best to use fertilized and water-retaining ponds with slow-moving water. For grass carp and silver carp, shallow and flowing water ponds are more suitable. Ideal pond size ranges from 5 to 7 acres, with a depth of about 1.5 meters. The layout should be rectangular, oriented east to west. Eel breeding ponds should have about 20 cm of silt to enrich the water, while grass carp and bighead carp ponds should have minimal or no silt.
Second, stocking density is an important factor. Broodstock should be raised in ponds along with a small number of other fish species to maintain balance. The total weight of broodstock per acre should not exceed 160 kg. If there are wild fish present, a few individuals like mullet or salmon can be introduced to help control algae and maintain water clarity.
Third, broodstock feeding and care require careful planning. Fertilization is the main method for cultivating broodstock. In oyster ponds, about 70% of the fertilizer comes from manure, while livestock manure makes up the remaining 30%. In squid ponds, chicken manure is the primary fertilizer, accounting for about 70%, with human waste making up the rest. Fertilization should be adjusted based on water color and temperature, typically once a week at around 120 kg per acre. The ideal water color for carp ponds is yellow-green or oil-blue, while for silver carp, it should be dark brown.
Feeding practices vary depending on the species. Grass carp are fed malt, grain sprouts, and bean cakes in early spring, supplemented with vegetables and lettuce. Each fish should receive 50–100 grams of food daily, placed on a fixed feeding platform. As the season progresses, they are fed rye grass, water grass, and other green feeds, with a ratio of 20:1 between green and fine feed. Daily feeding amounts should be about 30% of their body weight, and feeding should last approximately two hours.
Silver carp and bighead carp are mainly fed snails, clams, and quail meat, with supplements such as bean cake or commercial pellets. Regular monitoring of feeding behavior and water quality is essential. Water should be flushed every two months, replacing half the old water with fresh water to maintain a depth of about 1 meter. This helps raise water temperature and improve nutrient cycling, promoting gonad development.
Ponds should be inspected twice daily to monitor feeding activity and water conditions. If signs of stress, such as floating heads, are observed, new water or an aerator should be added immediately. Every two weeks, after feeding, the feeding area should be disinfected using bleach or copper sulfate at a rate of about 250 grams per pond to prevent disease outbreaks.
By following these detailed practices, breeders can significantly enhance the health and productivity of their broodstock, ensuring successful spawning and better yields in the coming seasons.
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