Introduction of polyculture of Penaeus vannamei and grass carp

The polyculture between Penaeus vannamei and grass carp can increase the pond loading capacity, the polyculture water quality is relatively stable, the pH value, the species and quantity of plankton in the water change very little, and white prawns and grass carp are not susceptible to disease, the risk of polyculture is relatively small, and the economic benefits Relatively high.

With the maturity of the freshwater culture technology of Penaeus vannamei, the area of ​​freshwater cultured Penaeus vannamei is expanding year by year. However, in recent years, the seedling density of shrimp seedlings has increased significantly year by year, resulting in frequent occurrence of prawn disease. This has brought great losses to shrimp farmers. In order to prevent the occurrence of white shrimp virus disease and improve the comprehensive benefits of pond culture, in 2009, we conducted a polyculture test of Penaeus vannamei and grass carp and achieved good economic benefits. The relevant technology is introduced as follows:

First, materials and methods

Pond conditions

The pond has an area of ​​12 acres, rectangular, 2.5 meters deep, flat bottom, easy access to water, adequate water, good water quality, equipped with three sets of three-kilowatt impeller type aerator.

2. Clear pond disinfection

At the beginning of March, the sludge from the bottom of the pool was cleaned by a mud pump. After drying in the middle and late April, the influent water was 20-30 cm. After soaking with the tea seed cake, the whole pond was splashed with 20 g/m3 to kill the wild fish. Two days later, the water was filtered through a 80-mesh sieve to a depth of 1 meter and then disinfected with 600 g/mu of dibromohydantoin.

3. Cultivation of food organisms

At the end of April, chicken baits after fermentation were used to cultivate basic bait organisms, applying 20 kg per acre. When the water temperature reaches 16°C or higher, live bacteria are applied depending on the type and amount of plankton in the water. If the water color is too thick, the transparency of the water body is too low to apply Bacillus; if the water color is light, the transparency of the water body is too high, and photosynthetic bacteria should be applied. A few days later, the water color was light green, and the water body was transparent 20 cm to 30 cm. The plankton in the water was dominated by green algae and golden algae. The small branch angles began to multiply, and the water quality reached tender, cool and live. During the cultivation of food organisms, the aerator is opened at noon every day for 2 hours to 3 hours, which is conducive to the proliferation of food organisms.

4. Seed stocking

At the beginning of May, when the water temperature was stable above 18°C, the Penaeus vannamei seedlings were released based on the dietary biomass of the pond water (a certain number of small cladocera species). Specifications are body length 1.0 cm -1.2 cm, stocking 50,000 acre. Around mid-June, when the body length of P. vannamei reached 4 cm or more, the 2nd-age grass carp was put in, with a specification of 3–4 tails/kg and stocking of 500 fish per acre.

5. Water quality regulation

(1) In the early stage of cultivation, add water 30 cm-40 cm every 7 days. After adding water, use bio-fertilizer and photosynthetic bacteria fertilizer to keep the pool water to a certain degree of fatness. Before the release of grass carp seedlings, the pond is filled with water and the water depth reaches 2.4 meters. In the early stage, we must also pay attention to oxygenation. Everyday, we must open the aerator for 2 hours to 3 hours at noon. We must start the aerator for 4 hours to 6 hours at night, increase the time for the aerator to increase in rain on cloudy days, and apply 0.5 kg of aerobic particles per acre at night. .

(2) During the middle period of aquaculture, due to evaporation and leakage, water is stored every 10 days and added to the highest water level. After adding water, if the water is thicker and the water body is less transparent, the water body is disinfected with the chlorine preparation; if the water is light, the water body is highly transparent, and the water body is disinfected with the bromine preparation. The medium-term aquaculture is the most critical period in the aquaculture process. It is necessary to maintain the stability of water quality and high dissolved oxygen in the water. Open the aerator for 2 hours to 3 hours in the morning, open the aerator for 2 hours to 3 hours at noon, and open the aerator for 8 hours to 10 hours in the night. Open the aerator for overcast days and rain. Apply 0.5 grams of aerobic particles per acre per night, double use in rainy days.

(3) In the late aquaculture, in early August, the water temperature dropped, the plankton breeding in the water was slow, and the water quality changed little. Store water every 15 days and fill the pond. After adding water, use different disinfectants according to the amount of plankton and water quality in the water, so that the water quality will remain “fat, live, tender and cool”. Open the aerator for 2 hours to 3 hours in the morning, open the aerator for 2 hours to 3 hours at noon, open the aerator for 6 hours to 8 hours in the night, open the aerator for overcast days, and use aeration particles 0.5 acre per acre at night. kg.

6. Feed feeding

When Penaeus vannamei reached more than 3 cm, high quality Penaeus vannamei feed was selected. Before the fry was released, the diet with a crude protein content of 40 was fed and began to be fed twice a day, gradually increasing to four times. The amount of feed was increased or decreased according to the shrimp dish leftovers and the satiation of the shrimp. After the fry was released, grass carp was fed with a crude protein content of 28 grass carp and fed 4 times a day at 6 o'clock, 10 o'clock, 14 o'clock, and 18 o'clock. The bait feeder moderately cast slowly to prolong the feeding of grass carp. It is generally controlled between 1.0 and 1.5 hours. When the grass carp came into power, the pond was fed with a crude protein content of 32 white shrimps. After one month, according to the grass carp (without dead fish), the crude protein was gradually increased to 38, and increased at 22 o'clock at night. Shrimp material. Feeding amount is generally controlled to 80% fullness in grass carp and white shrimp.

7. Disease prevention and treatment

It mainly adopts the principle of “preventing the main thing and treating it as the supplement”. First of all, to stabilize the water quality, the water color, transparency, and PH value need to be relatively stable during the entire culture process, and the water should maintain high dissolved oxygen. Second, three yellow powder, Baoganling, and florfenicol should be regularly added to the grass carp bait. EM bacteria and bacillus bacteriophages were regularly added to the shrimp bait, and the bait was fed for 3 days every 15 days. Finally, after the grass carp was released, the water body was periodically sterilized with chlorine preparations, bromine preparations and the like, once every 10 days.

Second, the results

On September 15th, he began to use nets to pull fishing nets and dry ponds 7 days later. The total production of grass carp 6144 kilograms, the average yield of 512 kilograms, specifications for 1.2 kg / tail, the survival rate was 85.3, the total yield of 3864 kilograms of white shrimp, the average yield of 322 kilograms per mu, specifications of 60 / kg, the survival rate was 38.6, the total The output value is 133,000 yuan, the mu output value is 11,000 yuan, and the mu profit is 0.6 million yuan.

Third, summary and discussion

1. Feasibility of Polyculture of Penaeus vannamei and Grass Carp

Penaeus vannamei live mainly at the bottom of the pond. It only swims to the poolside or upper-middle waters when it is foraging. Grass carp is a pelagic fish and it is mainly in the upper waters of the pond. The two living waters can use the pond's load capacity better. . White grass carp was only released after 4 cm and it had little effect on the survival rate of white shrimp. It was proved that the polyculture of white shrimp and grass carp is feasible.

2. Analysis of the effects of polyculture on diseases

Through several years of aquaculture practices, we found that the water quality of polyculture between white shrimp and grass carp was relatively stable, and the pH value, the type and amount of plankton in the water changed very little, and both white prawns and grass carp were not susceptible to disease. During the cultivation process, grass carp can also eat weakly prawn, which reduces the incidence of white prawns.

3. Scientific feeding

Ensuring feed science feeding is an important factor in the success of polyculture. In this experiment, after the fry was released, the crude protein content of the shrimp was adjusted so as to prevent the high-protein shrimps from adapting to the disease. When feeding, try to avoid grass carp patrolling to eat shrimp. When the grass carp is adapted, gradually raise the shrimp material. protein.

4. Analysis of polyculture effects

In breeding practice, the risk of intensive culture of Penaeus vannamei and grass carp is relatively large, while the risk of polyculture between Penaeus vannamei and grass carp is relatively small, and the economic benefit is relatively high.

5. Analysis of quality of commercial fish and shrimp

The grass carp obtained through polyculture has a short and thick body, delicious meat, and better market sales. The color of the white shrimp is yellow-brown, and its specifications are moderate. The market sales are very good. It is suggested that at the beginning of September, most of the grass carp should be out of the pool (pulled into the fishing pool for fishing and can increase the income) with the netting and cutting table, and the remaining prawns can be kept alive. The commercial specifications for white shrimp come from the end of September to the beginning of October.

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