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Breeding techniques of carp fry
First, hatching ring (barrel) nursery.
The hatching ring is a specially designed body of water that mimics natural ecological conditions and keeps the eggs in constant motion. Using this method directly raises fish fry in an environment that closely resembles their natural habitat. More importantly, it provides a controlled setting that supports optimal growth and development for salmon fry.
When the carp seedlings begin to feed, they are given palatable bait fish—small live fish that have been removed from the film. This not only meets their nutritional needs but also helps maintain clean and fresh water conditions. However, it's important to monitor feeding carefully, as overfeeding can lead to poor water quality.
During the seedling cultivation process, special attention must be paid to the limitations of the hatching ring system, such as the lack of proper drainage and the risk of silt and organic matter buildup. After 5 to 7 days of rearing, it's best to choose a sunny day and rotate the ring around 10:00 a.m. Since the seedlings are very active and tend to eat a lot, it’s recommended to stop feeding the bait fish 12 hours before rotation to ensure they have an empty stomach and reduce potential losses.
Second, net cage nursery.
Net cages are an excellent option for raising fish seedlings, as they provide a steady supply of food and allow for continuous water exchange. However, one drawback is that you cannot feed them with newly released fish, which may require additional preparation. Regular cleaning and replacement of the cages are necessary, making management more complex and labor-intensive.
Most net cages use a three-stage nursery system. The first stage involves Class I boxes made from 40 to 28 mesh per 3 cm polyethylene netting, measuring 4 to 6 meters long, 1 meter wide, and 1 meter deep. The second stage uses Class II boxes made from 0.3 cm wide warp-knitted polypropylene mesh, sized 2 meters by 1 meter by 1 meter. The third stage consists of slightly larger boxes made from 0.5% wider mesh, also 2 meters by 1 meter by 1 meter. The ratio between these stages is typically 1:10:20, ensuring efficient space utilization and growth progression.
Third, cement pool nursery.
Cement pools are commonly used for fish breeding and usually measure around 4 meters by 6 meters with a depth of 0.8 meters, though sizes can vary slightly. The bottom should have a slight slope to facilitate drainage. A dedicated seedling pool should be located at the drainage area, along with proper drainage facilities. The drainage system is typically composed of a rubber hose, filter mesh, and support wire. The rubber hose is fixed at the center of the wire frame to prevent it from floating or shifting in the water. The water level is maintained by controlling the number of drains and the height of the outlet.
Fourth, small earth pond breeding.
Once the eel reaches about 3 centimeters in length, it can be transferred to a small earthen pond. The stocking density is generally around 150,000 eels per hectare. Before introducing the eels, bait fish must be pre-cultured in the pond. It is common to introduce the bait fish 10 to 15 days prior, with a density of 1,500 to 22.5 fish per hectare. Fresh water should be added regularly each day to maintain good water quality. Over time, if not managed properly, the water quality can deteriorate, so careful monitoring is essential.