Raising grass silver carp in cages in reservoir

The so-called "reservoir cage set box" is to set up four small cages in a large cage. "raising grass carp on top and raising silver carp below" means raising grass carp in small cages and raising silver carp in the upper and lower layers of small cages and large cages (5m in height of small cages, 5.5m in height of large cages and 0.5m in interlayer height). Grass carp in small cages are fed with pellet feed for high-density intensive culture, while silver carp in large cages mainly use grass carp stool and leaking feed as bait, not special bait, for grazing type sparse and rough breeding. This culture mode makes use of the different habits of different species of fish to maximize the feed utilization rate, and adopts the method of boxes to increase the three-dimensional culture space and unit culture capacity in water areas. it is a new mode and technology of energy saving, high density and reduction. Generally, 1 large box of 10mxlOmx5.5m and 4 small boxes of 5mx5mx5m, 1000 grass carp fingerling with 100~250g/ tail, 70 silver carp with 150-250g/ tail, and 1.

In the anniversary, the tail weight of grass carp and bighead carp reached 2-3kg and 1.5-2kg, respectively, and the survival rate was more than 95%.

First, the choice of water area.

The main results are as follows: 1. Choose the reservoir bay near the village, sunny leeward and water depth of more than 15m to install the cage. This is not only convenient for management, but also can avoid the bottom of the cage in the dry season (the normal rise and fall of the bottom is 3m).

2. Choose the water away from the waterway, wharf and current within the 0.1m/s. In this way, the water environment is relatively quiet and can reduce the stress response of fish.

3. The water area with polluting resources such as chemical fertilizer plant, paper mill and pesticide factory in the upstream and surrounding areas should not be selected.

Second, the production of net cages.

1. Cage material: 3x3 polyethylene nodular net is adopted.

2. Net cage specification: large box is pentahedral open type, box length 10m, width 1Om, depth 5.5m; small box is hexahedral closed type with box cover, box length 5m, width 5m, depth 5m; mesh 3cm.

3. Fishing raft structure: the bridge raft fishing raft is made up of foam big floating ball and pine board with 5mx5m frame. Generally, a fishing raft is equipped with 10 large boxes and 20-40 small boxes.

Third, the installation of cages.

The main contents are as follows: 1. The fixing of the large cage: after straightening and tightening the upper part of the cage, tie the angle rope of four angles to the pine board frame of the fishing raft, and tie the periphery of the cage on the edge of the frame with 0.25/7x3 polyethylene rope; hang 3-5kg heavy stones or sand bags on the outside of the four bottoms of the cage, so that the cage can be fully expanded and formed in the water.

2. Fixing of small cages: 4 small boxes are installed in each large box. The fixing method of a small box is the same as that of a large box.

3. The launching time of the cage: the cage should be installed 7-10 days before the fish box, so that the net becomes smooth after the attachment of algae, so as to avoid friction damage to the skin and scales of fish.

Fourth, the stocking of fish species.

1. Stocking time: generally choose to release @ # @ 233 fish species during the period from New Year's Day to the 15th day of the first lunar month of the following year. During this period, the air temperature and water temperature are low, the fish are strong, the scales are tight, and they do not like to struggle or jump. Fish are not easy to be damaged in net-pulling, counting, shipping and other operations, and the survival rate is high after stocking. Put grass carp first and then bighead carp.

2. Fish species specification: grass carp 100-250g/ tail, silver carp 150-250g/ tail.

3. Stocking density: 120-200 grass carp / m2 and 10 silver carp / m2.

4. Centralized hoarding: after the grass carp seedlings are purchased and shipped back, the grass carp seedlings should be concentrated in several cages with a density of 6-1000 pieces / m2 after being soaked in 5-10min with 3% Mel. 5% saline solution.

5. Vaccination: after the grass carp were concentrated for 3-4 months, the "quadruple" vaccine (vaccine to prevent rotten Gill, enteritis, red skin and bleeding) was injected and raised in boxes according to the planned density.

Fifth, feeding method.

1. Feed types: all grass carp pellet sedimentation materials with a protein content of 28% per cent and 30 per cent per cent were fed throughout the culture cycle. In the early stage of culture, the medium size 2.5mm was fed, and the large size 3.5mm was fed in the middle and later stages.

2. Daily feeding times and daily feeding quantity: the feeding power of grass carp is closely related to water temperature, climate, water environment and other factors. The water temperature is low, the weather is abnormal, the feeding power of fish is weak, the water temperature is high, the weather is good, the wind is calm, the feeding power of fish is strong. From May to September, the water temperature is high and the climate is good, which is the golden season for the growth of grass carp. At this time, it is usually fed three times a day, and the daily feeding amount is 6% of the total body weight of grass carp. After September before May, the air temperature is cold and the water temperature is low. At this time, the daily feeding amount is 3% and 5% of the total body weight of grass carp. In case of muggy heat, cold current, strong wind and heavy rain and other abnormal weather, you can reduce meals as appropriate.

3. Feeding method: the principles of "slow-fast-slow" and "less-more-less" should be mastered in feeding. In the early stage, before all the fish rose to the surface and scrambled for food, the feeding speed was slower and the feeding amount was less; in the middle stage, the fish were all floating and ferocious, and the feeding speed was faster and the feeding quantity was more; in the later stage, most of the fish had been full and sinking, leaving only a few small weak ones not yet full, so the feeding speed could be slowed down and the feeding amount reduced. During feeding, methods such as splashing water or tapping on the frame can be used to make a food-inducing sound to form a conditioned reflex, so that the fish can float and grab food in time and as a whole.

VI. Daily management

Grass carp can feed on the algae attached to the walls of the box, so there is no need to wash the box during culture. The daily management work is mainly to carefully observe and check whether the net clothing is damaged and slippery, and repair it in time if so.

VII. Disease prevention and control

After the grass carp was vaccinated, the immune protection of grass carp could reach more than 14 months, and there was no disease in the whole culture period. For the sake of safety, you can adhere to regular external prevention. There are two main external elimination methods commonly used in production:

1. Bleach hanging bag disinfection: 150-250g bleach is packed in each bag, hung in the upper corner of the cage, the medicine bag is filled with water for about 1m, and 2 bags are hung in each small box, adding medicine every 3-5 days.

2. Sprinkle quicklime regularly: disinfect each time for 3 days every 7-10 days, and sprinkle each small box with 2~3kg quicklime while it is hot every day.