Indoor zero drainage Australian freshwater crayfish factory breeding technology

Indoor zero drainage Australian freshwater crayfish factory breeding technology

Huang Zhipeng and others

Through the research on the indoor breeding technology of Australian freshwater crayfish and related materials, the author summarizes a set of economical and practical indoor zero drainage Australian freshwater crayfish factory breeding methods for the majority of practitioners to learn from and reference. [Yoshiyama Huayao self-media network debut]

1. Aquaculture water system

This is an efficient and environmentally friendly breeding method that reuses the daily breeding water in the Australian freshwater crayfish farming system after it is filtered, disinfected, and eliminated nitrogen, and then returns the filtered water to the breeding system for reuse. The traditional fully enclosed circulating aquaculture system is a high-cost, high-tech breeding method that integrates aquaculture, equipment transformation, microbiology, mechanical automation, environmental science and other multi-technology intersections.

Although biological, physical, chemical and other methods can be used to purify water bodies, due to its high technical content and high equipment cost, it is still impossible to promote and apply it in a wide range of farmers and enterprises.

The high-efficiency aquaculture water system designed in this study is based on the premise of economy, practicality and easy promotion, and has the advantages of low cost, low water consumption, energy saving and emission reduction. It aims to promote the development of Australian freshwater crayfish in China's freshwater shrimp market by simplifying and optimizing the fully enclosed circulating aquatic aquaculture system and cooperating with the efficient and large-scale Australian freshwater crayfish seedling technology for the majority of farmers and enterprises.

1. Breeding system

The daily breeding pond is mainly based on the traditional indoor breeding pond, but the inlet and drainage need to meet certain requirements, based on the biological habits of the Australian freshwater crayfish benthic, the daily breeding water requires the inflow through the upper layer of the pond water, the outflow from the bottom of the pool, and the maximum exchange of the bottom water body. Therefore, in the breeding process, this breeding experiment uses a double casing structure of supporting specifications, with the inner casing controlling the water level and the outer casing controlling the underlying flowing water. The outgoing water flows through the pipe into the water treatment system.

2. Filtration system

After the daily breeding water flows into the filter pond, the residual bait and feces are first filtered through the primary filter tank, and the primary filter pond uses the biological filter as the filter filler. It then flows into the secondary filter pool, where the filter filling material is an artificial sponge to further filter the fine residue. After two-stage filtration, the filtered water enters the temporary reservoir, and the waterproof ultraviolet disinfection lamp is installed in the temporary reservoir, which also plays a preliminary disinfection and sterilization role.

3. Nitrogen elimination system

The nitrogen elimination system mainly removes excess ammonia nitrogen and nitrite from the filtered water through the nitrification and denitrification of microorganisms. After repeated disinfection and sterilization of the filtered water by the temporary reservoir, and then pumped into the nitrogen elimination device through the submersible pump, the nitrogen elimination system is mainly based on a fully enclosed water tank (diameter 20 cm, height 3 m) and filled plastic biofiltration membrane filler or biological filter. Inoculate nitrifying bacteria 1 to 2 weeks before the filtration system is run to achieve the purpose of building a stable microbial filter membrane in the filler of the water tank.

4. Reservoir (disinfection and sterilization tank)

The filtered water after nitrogen elimination treatment eventually flows into the reservoir, which also plays the role of final disinfection and sterilization. First of all, a number of aerosol stones are installed in the reservoir to aerate the final treated aquaculture water and discharge small molecules of toxic substances through gas action. In addition, the water in the reservoir is regularly disinfected and sterilized, mainly by disinfecting and sterilizing with strong aquatic disinfection supplies such as strong chlorine or chlorine dioxide, followed by large aeration and the addition of sodium thiosulfate to remove residual chlorine. The filtered water treated by the above filtration system is then pumped into the australian freshwater crayfish farming pond through the submersible pump to meet the daily water consumption of Australian freshwater crayfish.

Second, Australian freshwater crayfish artificial breeding

This paper mainly optimizes and improves the factory batch breeding technology of Australian freshwater crayfish on the basis of the actual production summary, combined with the efficient breeding water system, in order to achieve the purpose of large-scale production of fry. After three months of indoor breeding experiments, the egg holding rate of female australian freshwater crayfish was (87.33±1.73%), and the hatching rate of shrimp fry was (95.33±2.03%); through the reasonable combination of open bait, the survival rate of the epimeal shrimp when it grew to more than 2 cm was (93.33±2.02%).

1. Management and nutrition of broodstock

Select broodstock of Australian freshwater crayfish with 70 to 90 g/tail size, complete appendages and robust physique, and distinguish between male and female (male shrimp with large claws and transparent and soft red film at the front end; female shrimp claws are small and have no obvious red film), and then male and female are isolated and reared for pre-breeding nutritional fortification. The stocking density must be reasonable, where the stocking density of female shrimp is 5 fish/m

2 is advisable, male shrimp

Stocking densities range from 10 to 15 fish/m

2 is advisable. In terms of breeding conditions,

Each breeding pond guarantees long-term micro-flowing water, the depth of the water body is about 30 cm, the water temperature is 20 ~ 22 ° C, each breeding pond is designed with several gas stones to ensure that the oxygen of the daily water body is sufficient, and the bottom of the breeding pond is laid with sufficient avoidance (bamboo tubes, tiles, PVC pipes, etc.).

After anatomical experiments on a number of female shrimp one week after childbirth, it was found that there were large differences in the postnatal gonadal development period of female Australian freshwater crayfish, most of which were in stage II and a small part in stage IV. Therefore, it is particularly important to separately breed male and female broodstock separately before birth and carry out nutritional fortification to promote the gonads into stage IV. In the production process, the nutrient fortification is mainly carried out by micro-flowing water + broodstock compound feed + a small amount of corn, and the strengthening time is appropriate for 2 to 4 weeks.

2. Broodstock pairing and reproduction

The area of broodstock pairing pond is about 20 m2, of which the ratio of male and female broodstock is 2:1, and the pairing density is 6 to 9 /m2. And after a week of pairing, the water temperature is gradually raised from 20 to 22 °C to 25 ~ 28 °C, and the light time during the day is extended to 14 hours / day. After two weeks of breeding in pairs, check the mating of the broodstock and the development of the fertilized eggs.

After the australian freshwater crayfish is mated, the fertilized eggs are in vitro fertilized and develop in vitro. The stages are briefly described as follows: First, after mating is completed, the female shrimp is above the ovulation hole, the third step is to retain a milky white sperm pod at the base of the foot, and then a bean-green egg is released from the ovulation hole. After the egg is fertilized, the color of the fertilized egg develops to earth yellow, followed by the differentiation of animal poles and plant poles, and the yolk cells gradually develop to orange-red. Therefore, in the process of artificial seedling breeding, the female shrimp with eggs can be distinguished by distinguishing the development stage of the fertilized eggs of the female shrimp holding eggs, and the female shrimp with eggs at the appropriate development stage can be selected and entered the hatching pond to hatch the shrimp fry.

3. Hatching and shrimp fry rearing

Since the digestion and immune function development of Australian freshwater crayfish have just emerged from the membrane shrimp have not yet been completed, in order to ensure the survival rate of broodstock and shrimp, we will set up two sets of independent water treatment systems for broodstock breeding and shrimp hatching water, and the breeding water does not interfere with each other. In addition, 10 g/m must be used before the egg-holding female shrimp are moved into the hatchery tank

3 The hatchery is filled with potassium permanganate at a concentration

Divide the cleaning and disinfection. Subsequently, the water temperature of the hatchery is adjusted to be consistent with the water temperature of the pairing pond for shrimp hatching. Under the water temperature condition of 28 °C, the fertilized eggs can be hatched after 21 to 25 days to emerge from the membrane, and the body length of the shrimp is 0.7 to 0.8 cm, and the tail weight is about 0.07 grams.

Due to the large size of the Australian crayfish fry that has just emerged, it has the ability to feed on No. 0 shrimp feed. In the traditional Australian freshwater crayfish nursery, many farmers directly mark coarse shrimp fry by spilling soy milk or feeding No. 0 shrimp feed. Affected by the fragile intestines of Australian freshwater crayfish fry and the incomplete development of digestion capacity, the survival rate of shrimp fry is greatly reduced. In this culture experiment, the newly released baby shrimp were collected into the standard coarse breeding pond, and the stocking density was 200 to 300 fish/m2. With a certain proportion of shrimp slices, algae powder and multivitamins, the crude protein content is about 45%. After being filtered by a 250-mesh mesh of silk net before feeding, it is dissolved in breeding water and then sprinkled and fed, and the daily feeding amount is 5% to 10% of the total weight of the piglet shrimp. After 21 days of open powder feeding, the tail weight of the piglet shrimp was 0.169 grams, the weight gain rate was 245.99%, and the survival rate reached more than 95%.

3. Discussion

Compared with other water treatment systems, the factory breeding technology of Australian freshwater crayfish based on efficient aquaculture water system discussed in this paper has the characteristics of simplicity, ease of operation and replicability, and is also easily accepted by the majority of Australian freshwater crayfish practitioners because of its low construction equipment cost. However, in order to ensure the survival rate, spawning rate, hatching rate and ensure the stability of the entire water filtration system in Australia, there are still noteworthy links and improvements in the actual breeding process.

First of all, the filter material of the filtration system is more commonly used, and the molecular size of the filter is very limited. Therefore, an additional pump can be installed in the temporary reservoir to pump the filtered water again into the class I filtration and class II filtration system for repeated flushing. In addition, it is recommended to regularly clean, disinfect, replace biological filters and artificial sponges, and clean the sediment residue of the temporary reservoir regularly. A breeding system is recommended to be paired with two filtration systems to ensure the effectiveness of filtration of aquaculture water. In addition, in the process of cultivating the biological filter membrane, the nitrogen elimination system recommends a variety of beneficial bacteria inoculation, such as Bacillus, lactic acid bacteria, etc. Excess small molecule organic matter in filtered water can be consumed more efficiently, ensuring that pathogenic bacteria do not breed in the water filtration system.

In the daily management of Australian freshwater crayfish farming, it is also necessary to pay attention to the monitoring of water quality, regularly detect the water quality of the entire breeding system, and maintain the stability of the entire breeding system. Therefore, the following points must be paid attention to during the breeding process: (1) Regular disinfection. Every 1 month or so, sprinkle the whole tank with 10 g/m3 concentration of potassium permanganate. (2) Regular supplementation of calcium elements. Sprinkle the whole pool with 20 g/m3 quicklime every 1 month or so. (3) Strictly control the feeding time and feeding amount. Australian freshwater crayfish are nocturnal, so the daily feeding volume is about 2% of the total weight, of which 25% of the bait is fed during the day and 75% of the bait is fed at night. And after feeding the feed for 2 to 3 hours, the residual bait and feces are sucked out of the pond in time to ensure the cleanliness of the breeding pond.