CN113907022A

CN113907022A - Seedling raising method for incubating groupers by adopting chlorella

Info

Publication number: CN113907022A
Application number: CN202110672512.2A
Authority: CN
Inventors: 黄成潭; 潘军; 叶蕾; 黄敏
Original assignee: Hainan Green Algae World Biotechnology Co ltd
Current assignee: Hainan Green Algae World Biotechnology Co ltd
Priority date: 2021-06-17
Filing date: 2021-06-17
Publication date: 2022-01-11

Abstract

The invention relates to the field of grouper cultivation, in particular to a seedling cultivation method for hatching groupers by adopting chlorella. The invention applies the self-produced natural green microalgae products to the indoor industrial breeding link of the groupers, breaks through the difficult problems of extremely low incubation survival rate, serious pollution and the like of the groupers, gets through the whole indoor industrial breeding process and provides assistance for indoor industrial breeding transformation of the groupers.

Description

Seedling raising method for incubating groupers by adopting chlorella

Technical Field

The invention relates to the field of grouper cultivation, in particular to a seedling cultivation method for hatching groupers by adopting chlorella.

Background

The grouper belongs to the order Perciformes, lives in temperate and tropical sea areas, and inhabits in gaps between coral reefs and seabed broken stones, and does not migrate for a long distance. The grouper body is a warm water large and medium size marine fish with color change, brown or red, stripes and spots. The grouper is rich in nutrition, tender and white in meat quality, similar to chicken, and called sea chicken as vegetarian. Grouper is considered a valuable marine product on the market. The grouper is a high-quality edible fish with low fat and high protein, and is one of four major fishes in China. The grouper is often in high-grade hotels and restaurants, has high selling price and short supply and demand, and the grouper breeding industry develops rapidly under the pull of economic benefit.

The grouper culture is the fourth major breed in China at present, and in recent years, as the demand of the market for groupers is continuously increased, the yield of the groupers in China is increased year by year. The annual culture increment of the grouper exceeds 21 percent, and the growth rate of the grouper is far superior to that of the prior perch and flounder. Grouper became the only continuously and rapidly growing breed in addition to large yellow croaker.

At present, the outdoor incubation of grouper in an external pond (the process from roe to No. 03 fry screening) is influenced by factors such as weather, water quality, baits and the like, so that the incubation success rate is extremely low. The survival rate of the hatched fry is basically lower than 5 percent, and the fry quality is not high. At present, the survival rate of the seedlings is 12.5 percent only once by the most successful marine fishery test center in Guangdong province after the seedlings are incubated in indoor factory circulating water, but the success rate of the seedlings is low due to various problems.

The process that grouper is bred from 03# (3 cm) young fry to 15 cm is called standard thickness, the stage of changing 03# young fry into 4-5 cm fry is extremely easy to cover the whole army, and the main reasons are two points:

1. the 03# plantlet is hatched from an outer pond, has potential virus infection risk or low constitutional immunity and is extremely easy to die.

2. At this stage, the seedlings have weak resistance and are more easily infected by harmful bacteria in external water. And the more infection, the more drugs are used by farmers, the greater the drug resistance of pathogenic bacteria, and the more polluted water is discharged to the coastal area, so that the quantity of pathogenic bacteria carried by exogenous water is also increased rapidly, and a vicious circle is formed.

After the 70 s in the 20 th century, research on artificial propagation of grouper was carried out successively in countries of southeast asia, kowit, china, and the like, and china was the earliest successful in terms of industrial production.

In China, the research on the artificial propagation technology of grouper starts in the 80 th century, the artificial propagation of grouper is firstly successful by the research institute of marine products in Zhejiang province, and then the artificial propagation of grouper and giant grouper is successful by the oceans in Chinese academy. The seawater fish breeding research team of Hainan university in Chenghua obtains the subsidy of hundreds of new agricultural technical projects in Hainan province in 1998, and starts to start the artificial breeding research of the grouper with the characteristics of Hainan and capable of being popularized.

The research and development of foreign varieties present a development trend of high yield and high quality, an international species system presents a development characteristic of 'taking an enterprise as a main body and integrating breeding and propagation', and an international species market pattern presents a monopolized development situation. And the development situation of the Chinese aquatic breeding industry is reflected: genetic breeding, the construction of an original improved variety system are gradually improved, breeding technology is innovative, and new variety cultivation is greatly advanced. But at present, the aquatic breeding industry in China still has a plurality of imported foreign fingerlings; the improved breeding level is not high, the genetic improvement yield is low, and the like, compared with the internationalized major breeding companies, most aquatic breeding companies are relatively small, and the core competitiveness and the industry advantages are not formed.

The traditional grouper hatching and breeding modes are mainly outer pond open-air hatching. The incubation success rate is extremely low due to the influence of factors such as weather, water quality, baits and the like. And even if the fry is hatched, the survival rate is basically lower than 5 percent, and the quality of the fry is not high. However, the survival rate of the seedlings is 12.5% only once by the marine fishery test center in Guangdong province after the current indoor factory circulating water incubation, but the success rate of the seedlings is low due to various problems. Meanwhile, extensive culture, frequent disease and insect damage and extremely low fry survival rate lead the quality of medicinal products contained in the fishes to be reduced and seriously pollute the water quality for storing illegal drugs such as antibiotics abused by the amount of the stored goods.

The success rate of the incubation link of grouper fries is an industrial difficulty, and the incubation success rate is low and very unstable, about 0.1-10%. The three stages of high mortality during hatch are fry opening stage, wing opening stage and wing collecting stage (table 1).

TABLE 1 incubation and fry rearing of grouper

The chlorella is rich in eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and other fatty acids necessary for the growth of fry, the application of the chlorella to the bait industry is extensively and deeply researched internationally, the commercial production of the chlorella is carried out in many countries, and the chlorella powder has been used as a healthy food and a good feed additive in countries such as America, Japan, Israel and China for more than 30 years. Microalgae culture is an important link in aquaculture and industrial seedling production, is an important aspect of solving the problem of baits in fish, shrimp and shellfish culture, particularly in the seedling culture stage, and the success or failure of microalgae culture is directly related to the success or failure of artificial seedling culture.

The seawater seedling raising method can not leave microalgae, but most farmers and enterprises cannot ensure stable supply of fresh microalgae in the process of hatching and seedling raising, so that algae powder is not selected for improving the survival rate of seedling raising. This is also a factor that causes high incubation failure rate, because amino acids and active substances lose activity due to high temperature in the process of preparing powder from microalgae at high temperature, nutritional ingredients of the algae powder are greatly reduced, and the expected seedling raising effect is not achieved finally.

The microalgae is used as excellent palatable bait for raising seedlings, and is mostly used in the seedling stage of the growth of fishes, shrimps, crabs and shellfish. The addition of the microalgae can improve the growth performance of the cultured objects, supplement insufficient nutrient components in the compound feed, reduce the feed cost, improve the survival rate, enhance the disease resistance, increase the body color, improve the quality of aquatic products and the like. For example, the key to the success or failure of clam seedling is whether a large amount of high-quality algae meeting the seedling requirement can be cultured; the survival of the prawn seedling enterprises is mainly determined by the cultivation effect of the prawn seedlings, the metamorphosis time, the vitality, the size of the head and the water quality of the fed unicellular alga prawn seedlings are superior to those of the prawn seedlings which are not fed, and the survival rate of the prawn seedlings directly influences the upper part and the lower part of an industrial chain. The unicellular algae is used as the most suitable bait for the early stage of the grouper fry, and if the grouper fry is properly cultivated, the cost can be saved, the environmental load of the water body for cultivating the fry is reduced, more importantly, the survival rate can be improved, and a solid foundation is laid for the development of the fry.

Disclosure of Invention

In view of the above, the invention provides a seedling raising method for hatching grouper by using chlorella. The method solves the problems of extremely low survival rate of incubated groupers, serious pollution and the like.

In order to achieve the above object, the present invention provides the following technical solutions:

the invention provides a method for hatching and raising grouper seedlings, which comprises the following steps:

insect breeding: temporarily culturing ss rotifers 3-4 days before spawns are put, and removing bacteria, viruses, organic impurities and dead insects by using a bactericide (bacterium gram);

laying eggs: selecting eggs, and ensuring that dead eggs (bottom-sinking eggs) in 1 metric egg of two insects are less than 40 eggs; the worm eggs are put into the purified seawater, and finally the density of the fish eggs in the water body is more than 7000 eggs/ton;

the day of egg laying is taken as the 1 st day; adding 50-100 g of photosynthetic bacteria (viable count is 1.0-2.0 × 10) from the day 2 of egg laying¹⁰cfu/g) and 50-100 g of bacillus (viable count is 1.0-2.0 x 10)¹⁰cfu/g) to make the concentration of each bacterium in the water reach 1000 cfu/ml;

adding chlorella in the morning every day from the 3 rd day of egg laying, and adding 1.2-1.5L of chlorella solution into each ton of water, wherein the density of the chlorella solution is 1400-2000 ten thousand cells/ml; after the addition is finished, waiting for 1 hour, sampling and detecting the density of the algae in the water body, and enabling the density of the algae in the water body to reach 5-10 ten thousand cells/ml;

adding rotifers every day from the 3 rd day of egg laying, and measuring the algae content once in the morning and afternoon to ensure that the algae content in the aquaculture water is more than 15-30 ten thousand per mL;

adding 10-30 g of EM (viable bacteria amount is 1.0-2.0 × 10) per day from the 3 rd day of egg laying¹⁰cfu/g)；

The addition amount of the chlorella is reduced day by day from the 10 th day of egg laying, and is reduced by 20-30% of the addition amount of the chlorella on the previous day every day until the addition amount of the chlorella reaches 1-2L of chlorella solution per ton of water, wherein the density of the chlorella solution is 1400-2000 million cells/ml;

gradually replacing the worms according to the size of the fry;

continuously changing water every day;

emergence of seedlings occurred on day 21 from egg laying.

In some specific embodiments of the invention, 30-50 g (the content of rotifers is not less than 1000/g) of rotifers per ton of water is thrown per day on the 3 rd-5 th day of egg laying, feeding the rotifers every 2-3 hours, monitoring the content of the rotifers in the water every 3 hours, and adding the rotifers when the content is lower than 20 rotifers per mL; lighting in the whole process;

the rotifer is screened by bagging filtration, the outer bag is 350 meshes, the inner bag is 250 meshes, and the rotifer sandwiched between the outer bag and the inner bag is taken.

In some specific embodiments of the invention, 30-50 g (the content of rotifers is not less than 1000/g) of rotifers per ton of water is thrown per day on the 6 th-7 th day of egg laying, 100g (the content of copepods is not less than 200/g) of copepods per ton of water is thrown, the feeding is carried out once every 2-3 hours, the content of insects in the water is monitored once every 3 hours, and the insects are additionally added when the content of insects in the water is lower than 20 rotifers per mL of water or lower than 2 fleas per mL of water; light is irradiated from 8 o 'clock in the morning to 7 o' clock in the evening;

the rotifer is screened by bagging filtration, an outer bag is 350 meshes, an inner bag is 250 meshes, and the rotifers arranged in an interlayer between the outer bag and the inner bag are taken; the copepods are screened by adopting a single bag with a 200-mesh filter screen.

In some specific embodiments of the invention, 30-50 g (the content of rotifers is not less than 1000/g) of rotifers per ton of water is thrown per day on the 8 th-9 th day of egg laying, 200g (the content of copepods is not less than 200/g) of copepods per ton of water is thrown, the feeding is carried out once every 2-3 hours, the content of insects in the water is monitored once every 3 hours, and the insects are additionally added when the content of insects in the water is lower than 20 rotifers per mL of water or lower than 2 fleas per mL of water; no illumination is needed;

the rotifer is screened by bagging filtration, an outer bag is 350 meshes, an inner bag is 200 meshes, and the rotifers arranged in an interlayer between the outer bag and the inner bag are taken; the copepods are screened by adopting a single bag with a 200-mesh filter screen.

In some specific embodiments of the invention, 15-30 g (the content of rotifers is not less than 1000/g) of rotifers per ton of water is thrown per day on the 10 th-13 th day of egg laying, 200-300 g (the content of copepods is not less than 200/g) of copepods per ton of water is thrown, the feeding is carried out once every 2-3 hours, the content of the pests in the water is monitored once every 3 hours, and the pests are additionally added when the content of the pests is lower than 2 copepods per ml of water; no illumination is needed;

In some specific embodiments of the invention, 300-800 g (the content of copepods is not less than 200/g) of copepods per ton of water is thrown in every day on the 13 th-20 th day of egg laying, the insects are fed every 2-3 hours, the content of the insects in the water is monitored every 3 hours, and the insects are additionally added when the content of the insects is lower than 2 copepods per ml of water; no illumination is needed;

the copepods are screened by adopting a single bag with a 150-mesh filter screen.

In some specific embodiments of the invention, 800-1500 g (the content of copepods is not less than 200/g) of copepods per ton of water is thrown in every day after 21 days of egg laying, the insects are fed every 2-3 hours, the content of the insects in the water is monitored every 3 hours, and the insects are additionally added when the content of the insects is lower than 2 copepods per ml of water; no illumination is needed;

the copepods are screened by adopting a 100-mesh filter screen and a single bag.

In some embodiments of the invention, the pH range: 8.2-7.8, wherein the daily fall amplitude cannot be larger than 0.15; DO range: 4.5-6 mg/L; ORP range: 100 to 300.

In some embodiments of the invention, the ammonia nitrogen range is: <0.15 mg/L; sub-salt range: <0.1 mg/L.

In some embodiments of the invention

Early stage (before wing collection): the upper limit of ammonia nitrogen alarm is as follows: <0.12mg/L, upper control limit: <0.15 mg/L;

sub-salt alarm upper limit: <0.06mg/L, upper control limit: <0.1 mg/L;

late stage (after wing collection): the upper limit of ammonia nitrogen alarm is as follows: <0.15mg/L, upper control limit: <0.2 mg/L;

sub-salt alarm upper limit: <0.06mg/L, upper control limit: <0.1 mg/L.

The invention applies the self-produced natural green microalgae products to the indoor industrial breeding link of the groupers, breaks through the difficult problems of extremely low incubation survival rate, serious pollution and the like of the groupers, gets through the whole indoor industrial breeding process and provides assistance for indoor industrial breeding transformation of the groupers.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below.

FIG. 1 shows the change of dissolved oxygen in water during cultivation;

FIG. 2 shows the change of pH of water during cultivation;

FIG. 3 shows the survival rate of the Chlorella used for grouper during the cultivation process.

Detailed Description

The invention discloses a seedling raising method for incubating grouper by chlorella, which can be realized by appropriately improving process parameters by referring to the contents in the text. It is expressly intended that all such similar substitutes and modifications which would be obvious to one skilled in the art are deemed to be included in the invention. While the methods and applications of this invention have been described in terms of preferred embodiments, it will be apparent to those of ordinary skill in the art that variations and modifications in the methods and applications described herein, as well as other suitable variations and combinations, may be made to implement and use the techniques of this invention without departing from the spirit and scope of the invention.

The following are differences between me product and the commercial product:

TABLE 2

The invention is further illustrated by the following examples:

EXAMPLE 1 Pre-culture preparation

1) Before egg laying, the hatching barrel is cleaned, and the air stone air cake and the lamp tube water pipe are connected.

2) Disinfecting the hatching barrel with bleaching water, soaking for 1 night, and draining.

3) And cleaning the hatching barrel again to ensure that residual bleaching water on the inner wall of the hatching barrel is cleaned.

4) And detecting whether the electric wire, the water pipe, the air pump and other equipment are normal.

Example 2 insect raising

Temporarily culturing ss rotifers 3-4 days before egg laying, cleaning and temporarily culturing rotifers introduced from an outer pond, screening and cleaning every day, and simultaneously adding a bactericide (Junke) to remove bacteria, viruses, organic impurities and dead insects.

Example 3 Day 1 spawning

1) One day before egg laying, the seawater is added into the hatching pond after being purified.

2) On the day of laying eggs, selecting and purchasing proper eggs, and detecting the fish eggs. The detection method comprises the following steps: few dead eggs (dead eggs: sinking or blushing), high permeability of live eggs, good suspension, full oocysts examined by microscope, and no empty cells or dead embryos. Ensure that dead eggs in each bag of worm eggs (1 cm and two) are less than 40 (eggs with sunk bottom)

3) And (3) calculating the egg consumption of the unit water body, uniformly mixing all the roes, and adding the roes into the hatching pond according to the calculated amount to ensure that the density of the roes in the final water body is more than 7000 roes per ton. The calculation method comprises the following steps: adding the roes into the water body, fully mixing for half an hour, scooping 500ml of water body by using a beaker, counting the quantity of the roes, and multiplying by 2000 to obtain the quantity of the roes in one ton of water body.

4) Setting an on-line sensor to ensure real-time data remote transmission and alarm, wherein the lower alarm limit is DO: 4.8, pH: 8.0.

example 4 Day 2-Day 3 addition of bacteria and algae

1) Starting on day 2, 100g of photosynthetic bacteria (viable count 1.0X 10) were added daily¹⁰cfu/g) and 100g of Bacillus (viable count 1.0X 10)¹⁰cfu/g) to ensure that the concentration of each bacterium in the water body reaches 1000cfu/ml

2) Beginning on day 3, supplementing chlorella products in the morning every day, and if 1.2-1.5L of fresh chlorella algae liquid (the density of the fresh chlorella algae liquid is calculated according to 1400-2000 ten thousand cells/ml) cannot be added into each ton of water body, recalculating the volume and adding. After the addition is finished, waiting for 1 hour, sampling and detecting the density of the algae in the water body, and enabling the density of the algae in the water body to reach 5-10 ten thousand cells/ml.

Example 5 Day 9 Add insect, fungus, algae

TABLE 3 Pest-feeding Process

Example 6 rotifer fortification: strengthening with Chlorella. Copepods (daphnia) augmentation: is prepared from Chlorella, Anguillar Japonica powder, shrimp flake, and yeast powder

1) The insects are added on the 3 rd day, and the feeding mode is shown in the feeding process in the table 3.

2) From the beginning of adding the insects, the adding amount of the algae is doubled, the content of the algae is measured once in the morning and afternoon, and if the content of the algae in the aquaculture water is more than 15-30 ten thousand per ml and is lower than the value, or the content of the algae is rapidly reduced in the afternoon, additional supplement is needed.

3) Adding EM bacteria 1-5ppm (g/ton water body) daily.

4) The water is changed, and the water is changed,

and starting a micro-flow water changing mode after passing the material: 1-2 upright columns with 400 liters are used for storing water, water in the upright columns is sucked into the culture pond in a siphoning mode, the stress on the fry is relieved by adjusting the water inlet rate, and the water changing process cannot be operated too fast every time and needs to be over 3 hours.

5) In the stage, the change of pH, DO and ORP is required to be paid attention to constantly to ensure that the pH and the DO are stable, and if the pH is in a descending trend, the algae liquid is required to be additionally supplemented. And if the DO is in a descending trend, checking whether the air pump is normal, adjusting the air outlet size of the air stone and maintaining the DO value.

The pH range is as follows: 7.8-8.5, wherein the daily fall amplitude cannot be larger than 0.15;

DO range: 4.5-6 mg/L;

ORP range: 100-300;

6) and detecting the ammonia nitrogen and the sub-salt condition of the water once every day. If the abnormity occurs, the system is rechecked once and reported in time.

The ammonia nitrogen range is as follows: <0.15 mg/L;

sub-salt range: <0.1 mg/L;

if ammonia nitrogen and nitrite continuously rise, emergency measures should be taken: increase the water change amount (water change proportion)

30-50 percent) and the water quality index is recovered to the set standard of the process.

Example 7Day 10-Day 20 adding insect, fungus, algae and water

1) Continuous water change

2) Reducing the consumption of fresh chlorella day by 20-30% each day (based on the previous day) until the addition of fresh chlorella per ton is 1-2L of fresh chlorella solution (the density of fresh chlorella solution is determined according to the standard)

1400-2000 ten thousand cells/ml), algae can not be stopped suddenly and can not be reduced quickly.

3) And gradually changing the insects according to the size of the fry, wherein the insect feeding is the same as the insect feeding process in the table 3.

Example 8 Day 21 emergence

1) Continuous water change

The ammonia nitrogen range is as follows: <0.2mg/L, sub-salt range: <0.1mg/L

2) According to the size of the fry, gradually changing bigger fleas, changing the feeding time of the worm into 3-5 times per day, and the feeding process is the same as the worm feeding process.

Example 9 Ammonia Nitrogen and sub-salt control

1) The water exchange amount at one time is not more than 30 percent.

2) When the fry is weak in the early period, the water change should be slow and stable, and after the fry is strong in the later period, the water change should be rapid (within half an hour), so that the high-concentration ammonia nitrogen sub-salt water at the bottom is exchanged.

3) And after the water is changed, detecting the ammonia nitrogen and the sub-salt conditions again, if the ammonia nitrogen and the sub-salt conditions are obviously reduced, achieving the control purpose, and if the ammonia nitrogen and the sub-salt conditions are not reduced or continue to rise, performing bottom suction operation (fully communicating with a field responsible person before bottom suction).

Early stage (before wing collection): the upper limit of ammonia nitrogen alarm is as follows: <0.12mg/L, upper control limit: <0.15mg/L

Sub-salt alarm upper limit: <0.06mg/L, upper control limit: <0.1mg/L

Late stage (after wing collection): the upper limit of ammonia nitrogen alarm is as follows: <0.15mg/L, upper control limit: <0.2mg/L

Sub-salt alarm upper limit: <0.06mg/L, upper control limit: <0.1mg/L

Effect example 1 dissolved oxygen

1) Adjusting a fan for feeding air to the culture pond to maintain the air pressure at 0.2-0.4 mpa;

2) and adjusting an air inlet valve of the culture pond to uniformly disperse the bubbles in the culture pond.

3) Algae addition was performed daily by examples 3-7.

The results are shown in FIG. 1.

In the incubation process of the grouper, the dissolved oxygen in the water body is maintained to be more than 4 mg/L. According to the figure 1, the dissolved oxygen is maintained above the normal value, and the water body dissolved oxygen level can be ensured by adding the chlorella. Meanwhile, the dissolved oxygen is shown to rise three days before the culture, the oxygen consumption is low in the process that the fish eggs are hatched to fish flowers, and the dissolved oxygen is at a higher level after chlorella is added. The later days, the oxygen consumption is increased after the fry is hatched, and the dissolved oxygen is continuously reduced because worms and EM bacteria are added and are oxygen consuming organisms. This also suggests that the amount of algae should be increased to increase the dissolved oxygen level of the water and reduce the ammonia nitrogen value of the water at the beginning of the fifth day of cultivation.

Effect example 2 pH value

The operations of adding algae and changing water are carried out through the embodiments 4 to 7;

the results are shown in FIG. 2.

The optimum pH range of the grouper hatching is 7.9-8.3. As can be seen from FIG. 2, the pH values are all in the proper range, but in the middle and later periods of cultivation, the pH value is obviously reduced and is lower than the optimal range. Meanwhile, the change height of the pH curve is consistent with that of the dissolved oxygen curve, and the pH curve is in obvious positive correlation with high dissolved oxygen, high pH, low dissolved oxygen and low pH. Because the chlorella absorbs acid radical ions such as carbon dioxide and nitrite in the process of photosynthesis, oxygen is generated, and the pH value of the water body is increased. The result is shown in figure 2, the process can maintain the pH of the aquaculture water body in the optimum growth pH range of the fry.

Effect example 3

Related experiments were performed according to the procedures described in examples 1-9. The results are shown in FIG. 3.

By the culture method provided by the invention, the survival rate of grouper hatching and breeding can be improved to more than 20% from the original 3%.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims

1. The method for hatching and raising the seedlings of the groupers is characterized by comprising the following steps of:

insect breeding: temporarily culturing ss rotifers 3-4 days before spawns are released, and removing bacteria, viruses, organic impurities and dead insects by using a bactericide;

laying eggs: selecting eggs, and ensuring that dead eggs in 1 male two eggs are less than 40 eggs; the worm eggs are put into the purified seawater, and finally the density of the fish eggs in the water body is more than 7000 eggs/ton;

the day of egg laying is taken as the 1 st day; adding 1.0-2.0 × 10 amount of live bacteria per day from the day 2 of egg laying¹⁰50-100 g of cfu/g photosynthetic bacteria and 1.0-2.0 multiplied by 10 viable bacteria¹⁰50-100 g of cfu/g of bacillus, so that the concentration of each bacterium in the water body reaches 1000 cfu/ml;

adding rotifers every day from the 3 rd day of egg laying, and measuring the algae content once in the morning and afternoon to ensure that the algae content in the aquaculture water is more than 15-30 ten thousand cells/mL;

adding viable bacteria 1.0-2.0 × 10 per day from the 3 rd day of egg laying¹⁰10-30 g of cfu/g of EM bacteria;

gradually replacing the worms according to the size of the fry;

continuously changing water every day;

emergence of seedlings occurred on day 21 from egg laying.

2. The method of claim 1, wherein no less than 1000 rotifers per gram per ton of water are thrown per day on the 3 rd to 5 th day from egg laying, the feeding is performed every 2 to 3 hours, the content of the rotifers in the water is monitored every 3 hours, and the rotifers are additionally added when the content is less than 20 rotifers per mL; lighting in the whole process;

3. The method according to claim 1 or 2, characterized in that not less than 1000 rotifers per gram per day 30-50 g/ton of water body are thrown per day from day 6-7 of laying eggs, not less than 200 copepods per gram 100 g/ton of water body are thrown, the feeding is performed once every 2-3 hours, the content of the rotifers in the water body is monitored once every 3 hours, and the rotifers per mL of water body or fleas per mL of water body are additionally added when the content of the rotifers is lower than 20 rotifers per mL of water body or lower than 2 fleas per mL of water body; light is irradiated from 8 o 'clock in the morning to 7 o' clock in the evening;

4. The method according to any one of claims 1 to 3, wherein 30 to 50 g/ton of water body is thrown in not less than 1000 rotifers/g per day and 200 g/ton of water body is thrown in not less than 200 copepods per day from 8 to 9 days of egg laying, the feeding is performed once every 2 to 3 hours, the content of the insects in the water body is monitored once every 3 hours, and the insects are additionally added under 20 rotifers/mL of water body or under 2 fleas/mL of water body; no illumination is needed;

5. The method according to any one of claims 1 to 4, wherein no less than 1000 rotifers per gram per day 15-30 g per ton of water are thrown per day from day 10-13 of egg laying, no less than 200 copepods per gram 200-300 g per ton of water are thrown per day, the feeding is performed once every 2-3 hours, the content of the worms in the water is monitored once every 3 hours, and the additive is added when the content is less than 2 copepods per ml of water; no illumination is needed;

6. The method according to any one of claims 1 to 5, wherein no less than 200 copepods/g are thrown per day at day 13-20, and the feeding is performed every 2-3 hours with the insects every 300-800 g/ton of water, the content of the insects in the water is monitored every 3 hours, and the insects are additionally added when the content of the insects is less than 2 copepods/ml of water; no illumination is needed;

7. The method according to any one of claims 1 to 6, wherein not less than 200 copepods per gram of 800-1500 g per ton of water are administered daily from day 21 of egg laying, the worms are fed every 2-3 hours, the worm content in the water is monitored every 3 hours, and the addition is made below 2 copepods per ml of water; no illumination is needed;

8. The method of any one of claims 1 to 7, wherein the pH range is: 8.2-7.8, the daily fall amplitude cannot be larger than 0.15; DO range: 4.5-6 mg/L; ORP range: 100 to 300.

9. The method according to any one of claims 1 to 8, wherein the ammonia nitrogen range is: <0.15 mg/L; sub-salt range: <0.1 mg/L.

10. The method of any one of claims 1 to 8,

sub-salt alarm upper limit: <0.06mg/L, upper control limit: <0.1 mg/L;

sub-salt alarm upper limit: <0.06mg/L, upper control limit: <0.1 mg/L.