In 2003, we implemented a scientific feeding and management system using full-price compound feed. We conducted trials to raise and domesticate grass carp fingerlings in ponds for carp farming. A total of 13,830 kg of large fish species were produced from eight acres of ponds, including 2,900 kg of grass carp, 8,600 kg of common carp, and 2,330 kg of white carp. The feed conversion ratios were 2.0 for grass carp and 1.8 for common carp. The survival rate of grass carp reached 75%, with a profit of 4,625.25 yuan per mu. This project marked the initial exploration of domesticating grass carp in carp ponds, successfully addressing issues such as disease and low numbers, improving water resource utilization, and increasing overall aquaculture profits.
**First, Pond Preparation**
The ponds used were located at Kuangxiang Company Farm in Lianyungang City, covering an area of 8 acres with a depth of 2.5 meters. The water source was abundant, and the quality was excellent, with convenient irrigation and drainage. Each pond was equipped with a 4-inch water pump, a 2.5kW aerator, and a 90W automatic feeder.
On April 22, the pond was cleared by removing excess silt, leaving about 10 cm of sediment. Quicklime (100 kg/mu) was applied to disinfect the pond. After draining most of the water, the bottom was kept at a depth of 10 cm. Small pits were dug at the bottom, and quicklime was mixed into a slurry and evenly distributed. On April 23, the mud was compacted with iron tools to ensure thorough mixing with the lime.
On April 24, the pond was filled with 0.6 meters of water after fertilization. The water was filtered through a 40-mesh sieve to prevent wild fish and harmful organisms from entering. A total of 400 kg/mu of fertilizer was applied to maintain a water transparency of around 25 cm.
**Second, Seed Stocking**
On May 2, 16,000 summer white carp were stocked at a density of 2,000 per mu. Two days later, 64,000 summer silver carp were added at a density of 8,000 per mu. On May 10, 32,000 grass carp fingerlings were introduced at a density of 4,000 per mu.
**Third, Domestication and Culture**
The domestication process started on May 11, using crushed pellet feed to train the fish to feed in the pond. Grass carp were gradually introduced to floating feed, starting with bran placed around the pond. Feeding began on May 18 using bamboo feed boxes. From May 20 onward, the floating compound feed was increased gradually, accompanied by sound stimulation to create a conditioned response.
By May 26, the domestication was largely complete, and the grass carp had developed a consistent feeding habit. Feeding occurred twice daily, with pellet sizes adjusted according to fish size—starting small and gradually increasing. The feeding time was controlled to about one hour per session. Carp and grass carp were fed separately, with the feeding stations 20 meters apart. Daily feeding amounts varied between 3% and 8% of the total fish weight, adjusted based on growth and weather conditions.
**Feed Requirements**
Squid were fed a specialized diet with 34% protein, while grass carp received feeds containing 28% crude protein and 9% crude fiber. The feed included fish meal, soybean cake, yeast, rapeseed cake, bran, grass powder, and other additives. Crude fiber helped improve digestion and metabolism in grass carp.
**Fourth, Breeding Management**
Water quality was managed carefully. From May to June, new water was added every 10 days. From July to September, water was changed every 7 days, with 30 cm of water replaced each time. Oxygen aerators were used strategically depending on temperature and weather. Water clarity was maintained at 20–30 cm, and the color was kept "green" or "red-green." Lime was applied every 15 days to control water quality.
**Fifth, Disease Prevention and Control**
In August, as feeding increased, so did the risk of disease. Quicklime and Bacillus spp. were used to break down organic matter and reduce harmful substances like ammonia and nitrite. These measures ensured a healthy environment and prevented any outbreaks of disease.
**Sixth, Cultivation Results**
Harvest took place in late November, yielding 13,830 kg of fish. Grass carp accounted for 2,900 kg with a survival rate of 75%. Common carp reached 8,600 kg with a survival rate of 94%, and white carp totaled 2,330 kg with a survival rate of 90%.
**Economic Benefits**
The feed conversion rates were 2.0 for grass carp and 1.8 for common carp. The net profit per mu was 4,625.25 yuan, with an input-output ratio of 1:1.59.
**Discussion**
This trial demonstrated that raising grass carp in carp ponds is feasible through staged stocking and domestication. It improved water use efficiency and breeding performance. Grass carp should be fed separately from squid, with feed stations at least 15–20 meters apart. Using pellet feed instead of green feed reduced water pollution and pathogen risks. Increasing crude fiber content in the feed supported better digestion and health. Preventive measures, including pond and fish disinfection, regular water treatment, and herbal additions, ensured disease-free production. The white carp-to-grass carp stocking ratio was set at 1:3, optimizing productivity.
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