Key Technical Points for Efficient Grass Carp Fry Breeding

How to efficiently breed grass carp fry? To efficiently breed grass carp fry, the following points should be achieved: pond site selection and disinfection, and selection and scientific management methods of grass carp water fry (newly hatched fry).

Do a good job in pond site selection and disinfection

1. Choose water from rivers, streams or reservoirs with sufficient water sources, fresh water quality, high dissolved oxygen and no pollution, and complete supporting facilities at the same time. The pond area is generally 1 to 3 mu, and a rectangular shape running east-west is preferable. The pond location should be relatively open and flat, well ventilated, with long sunshine duration, and the pond soil is preferably loam.

2. For the drug, block quicklime is preferred. Use the disinfection method with 150 kg/mu quicklime in water to kill bacteria, viruses and harmful organisms.

Selection of grass carp water fry

1. The most reliable way is to directly inspect the quality of the water fry. Take the water fry moved out of the hatching ring channel and temporarily kept in a net cage, take out a basin from the downwind side of the net cage and observe carefully. Good-quality water fry have normal body color, swim quickly and horizontally, move freely, and have no deformities.

2. Usually about 13 days after disinfection, it is the best period to release the water fry. In addition, the pond water temperature and the water temperature in the fry container must not differ by more than 3 degrees C; otherwise, place the fry container into the pond, and only release the fry with confidence after the two temperatures are basically the same.

Scientific management methods

1. The feeding and activity of the fry can be observed everywhere around the pond, so as to grasp the overall situation of the pond in a timely and accurate manner.

2. Within 1 week after stocking the fry, try every means to create an environment suitable for the water fry to live. If the water color has faded and there is very little plankton, promptly add more soybean milk or manure.

3. Properly feed artificial feed such as soybean milk, generally once in the morning and once in the afternoon each day, and gradually increase the feeding amount as the fry grow. In addition, cultivate fertile water to reproduce a large amount of natural feed. After about 10 days of cultivation, some have already begun to change their feeding habits. At this time, properly feed some duckweed and small duckweed to attract feeding. Make sure the green feed is clean and fresh, and strictly prevent disease from entering through the mouth. At the same time, closely observe the dissolved oxygen in the pond. When oxygen deficiency and floating head are serious in the pond, promptly add fresh water. In stuffy weather followed by a sudden thunderstorm, the upper and lower water layers in the pond convect, and a large amount of residue surges from the pond bottom to the water surface. The fry reduce feeding or basically stop feeding. This situation can easily induce pond turnover. In this case, immediately inject fresh water or turn on the aerator.

4. After about 1 month of cultivation, the fry have already completed the change in feeding habits, and the size is generally 3 to 4 cm. At this time they are summer fry. Apart from selling part of them, they must be divided among ponds for management, leaving only about 10,000 summer fry per mu to continue being cultivated into winter-spring fingerlings. Two days before pond division, carry out seining adaptability training. The operation should be light, quick and agile to reduce man-made injuries.

5. In terms of disease prevention, generally carry out routine disinfection methods. After autumn, feed once in the morning and once in the afternoon. After several months of careful breeding until winter, the fry basically reach 10 to 20 cm. Entering winter, the temperature is very low. If they are not to be released for the time being, combine the fingerlings in a relatively deep pond to overwinter and wait for release in spring.