How to raise high survival rate of water spray (small fry)?

Splash popular refers to the small seedlings from the hatching and shelling of fish eggs, which can generally be shipped under the fish ponds and delivered after shelling for 3-4 days, the body length is between 0.5-1cm, the whole body is translucent or light grayish black. If the spray is stored in the pool for too long after shelling, it will be very likely to weaken its foraging ability, growth and adaptability, so the spray should not be put into the pond for too long. How to raise water spray with high survival rate? We must understand the ten main points.

I. Design of fish fry pond

1. Fish fry pond requires solid dike, no leakage, sufficient water source, convenient injection and drainage, leeward, rectangle, east-west direction, fish fry pond should not be too large, too large is easy to form wind and waves, fish fry collide with the pool wall with the wind and waves, affecting the survival rate

2. The water level of Miao pond is too deep, and it is difficult to raise the water temperature. The area is too small, the water temperature changes quickly, and the living conditions of fish fry are difficult to control.

2. Clear the pond thoroughly before releasing the seedlings

1. Before stocking, fish fry should dry the pond water, remove weeds and dig out too much silt. Sprinkle the whole pond after 1500 kg of quicklime per hectare to kill germs, parasites and enemy organisms.

2. When entering the water, the inlet should be filtered with a double-layer dense net to prevent wild miscellaneous fish from entering the pond. after entering the fry pond, the pond should be inspected regularly every morning to find frog eggs and water plants and be removed in time.

Third, select and purchase high-quality seedlings

The quality of fish fry directly affects the survival rate of fish fry.

4. preparation of seedlings before they are put into the pond

1. Go to the pond after "testing the water": one day before the fry is released, take a few fry and put them in the cage of the fish pond and observe for one day. If the fish activity is normal, you can release the fry.

2. Fertilizer and water pond: the standard of fertilizer and water pond is that the zooplankton (rotifer) in the pond is in the peak period of reproduction, so as to ensure that the fish fry have sufficient palatable natural bait after entering the pond, which can improve the survival rate of fish fry cultivation. In general, rotifer reproduction reached its peak 6 ~ 7 days after fertilization in the fish pond, so the fertilization time should be 7 ~ 8 days before the fry went into the pond. If the water temperature is low, you can apply organic fertilizer 200 kg ~ 300 kg per mu 2 ~ 3 days in advance.

3. Eat enough to go to the pond: when the fry goes into the pond, feed 2 ~ 3 yolks for every ten thousand fry. The method is to put the fry into a larger plastic basin, dilute the yolk with water, filter it with 40 mesh polyethylene cloth, sprinkle it evenly in the basin, wait another 20 minutes and put it into the pond.

4. Adjust the temperature to the pond: when the fry is transported to the entrance of the pond, pay attention to the difference between the water temperature of the oxygen bag and the fish pond is not ±3 ℃. If the temperature difference is too large, put the oxygen bag on the surface of the fish pond. When the water temperature in the bag is close to the water temperature of the fish pond, slowly put the fish fry into the pond. In case of wind and waves, you should choose to plant seedlings 2 ~ 4 meters away from the shore.

5. Stocking density should be reasonable.

Fish fry cultivation generally only one species is cultured in a pond, which is not suitable for mixed culture. 80, 000 ~ 100000 fish fry are released per mu. Too low density can not make full use of water and bait, too high, it is easy to cause fish fry floating head, or due to lack of bait to inhibit the growth of fish fry.

6. put enough bait and apply fertilizer at the right time

Fish fry (spray) feeding time for the first time in the pond, two hours after the fry splash enters the pond, the fish can be fed with paste. According to the effective water surface of 667 square meters per mu (667 square meters), 4 kg ~ 5 kg of dried soybeans are used every day, and the dose of 18 kg of water made from 1 kg of soybeans is sprinkled evenly and meticulously on the whole pool. The ponds that release seedlings in the morning should be fed 2 ~ 3 times on the same day, and the ponds that release seedlings in the afternoon should be fed 1 ~ 2 times in the same day. After that, the fry were put into the breeding pond from the second day, and the dried soybeans were fed with the dose of 4 kg ~ 5 kg per mu (667 square meters) per day, and the time of each feeding was arranged as follows: 8: 00 in the morning, 12: 00 in the afternoon, 1:00 in the afternoon, and 4: 00 in the afternoon. Sprinkle evenly and meticulously on the whole pool for 3 consecutive days. After 3 days, the daily feeding amount should be increased or decreased according to the specific conditions such as fat and thin pond water, biomass (especially the number of rotifers) and the growth of pond fish. Whether the daily feeding amount is adjusted or not mainly depends on the water quality, the water level and the growth of fish.

VII. Regulation of water quality

In the early stage of fry entering the pond, the water depth is controlled at 40 cm ~ 60 cm, which is beneficial to the increase of water temperature and the growth and reproduction of bait organisms. After 7 days, water is injected once every 2 ~ 4 days, 10 cm ~ 15 cm each time, and the growth space of fish fry is enlarged. Keep the pond water "fat, alive, cool and tender". During water injection, attention should be paid to the straight flow of water into the pond, and the water injection time should not be too long, so as to avoid the top flow of fish for a long time, physical exertion, affecting growth or causing horse racing disease.

Master dissolved oxygen and cope with changes

The content of dissolved oxygen in the pond is an important condition for the survival, growth and development of fish in the pond. In order to achieve high yield and high efficiency in the high-density fish fry pond, the dissolved oxygen in the water body of the pond must be put in the same important position as the water in the daily feeding and management work.

The specific method is: look at water fertilization, timely transfer of water, master dissolved oxygen and start up in time. The value of dissolved oxygen in the water body of the breeding pond is always kept above 4.5 mg / L.

9. Patrolling the pond

The pond was inspected once every morning and evening to observe the water quality, to determine the amount of bait and fertilizer, to observe the activity and growth of fish, and to find out that the disease should be treated and cleared in time. The water in the pond should not be too fat. Silver carp will bulge, that is, the cannon. Just add water when the color is urgent like this. The water quality of the grass carp pond should not be too fat, and too much fertilizer will lead to the survival rate.

Do a good job in the prevention and control of fish diseases

In the summer flower stage of fish fry, the main fish diseases are horse racing disease, white head and mouth disease, white skin disease and so on. During the cultivation period, lime water is sprinkled once every 5 ~ 7 days, with 15 kg of quicklime per mu each time, which can clarify the water quality and prevent fish diseases. When horse racing disease occurs, Reed mat can be used to cut off the fry swimming route, stop water injection, and appropriately increase the amount of bait and fertilization. When white head and white mouth disease and white skin disease occur, sprinkle the whole pool with chlorine dioxide, bleach or strong chlorine, disinfect the pool water for 2 days, and divide the pool in time to reduce the density in the pool.