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 broodstock ponds should be carefully considered. The ponds should be located near a water source to facilitate drainage and irrigation, making it easier to maintain good water quality. For breeding species like eels and mudfish, it's best to use fertilized and water-retaining ponds with a shallow, slow-moving flow. Grass carp and silver carp, on the other hand, require ponds with minimal silt and clearer water. Ideal pond size is between 5 to 7 acres, with a depth of about 1.5 meters, and a rectangular shape oriented east to west. Eel breeding ponds should have approximately 20 cm of silt to enrich the water, while grass and blue carp ponds should have little or no silt.
Second, stocking density plays a key role in broodstock management. It's recommended to raise broodstock along with a small number of other fish species to promote a balanced ecosystem. The total weight of broodstock per acre should generally not exceed 160 kg. If wild fish are already present in the pond, a few small individuals such as mullet, salmon, or California salmon can be introduced to help control algae and maintain water clarity.
Third, proper feeding and fertilization are essential for broodstock development. Fertilization typically involves a mix of organic manure, with about 70% being farm waste and 30% being human excrement. In squid ponds, chicken manure is preferred, making up around 70%, with human waste accounting for the remaining 30%. Fertilization should be adjusted based on water color and temperature, ideally once a week at a rate of about 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 strategies vary by species. Grass carp should be fed malt, grain sprouts, and soybean cakes in early spring, supplemented with vegetable leaves and lettuce. Feed amounts range from 50 to 100 grams per day, placed on fixed feeding platforms. As the season progresses, they should be given more green feed like ryegrass and water hyacinth, mixed with fine feed in a ratio of 20:1. Daily feeding should be about 30% of their body weight, and feeding time should last around two hours.
For silver carp, snails, clams, and quail meat are the main food sources, with supplements like bean cake or commercial pellets. Water quality management is also crucial. Before the spring feeding season, half of the old water should be replaced with fresh water to maintain a depth of about one meter. This helps raise the water temperature and improves nutrient cycling in the pond. Regular water flushing—once every two months—is an effective way to stimulate gonad development. During flushing, the water flow should be moderate to avoid stressing the fish.
Finally, regular pond inspections and disease prevention are necessary. Each pond should be checked twice daily to monitor feeding behavior and water quality. If signs of stress or poor health are observed, such as floating heads, new water or an aerator should be added immediately. Every two weeks, after feeding, the feeding area should be disinfected using chlorine powder or copper sulfate at a rate of about 250 grams per pond. These measures help ensure healthy broodstock and successful breeding outcomes.
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