A method for large-scale seedling cultivation of *Pterocarya stenoptera*

Abstract

The present application belongs to the technical field of large-scale seed cultivation of shellfish, and discloses a large-scale seed cultivation method of Patella pellucida. According to the practical breeding experience, it is found that the main reasons for the failure of seed cultivation are high mortality in the plankton and attachment stages, the vulnerability of the water body to the invasion of protozoa, the easy outbreak of harmful algae in the water body and the like, which lead to the failure of the development of the juvenile stage to the benthic life. The present application successfully breaks through the bottleneck of the seed cultivation of Patella pellucida by optimizing the seed cultivation environment, improving the seed cultivation technology and controlling the light, and can cultivate the Patella pellucida seed on a large scale. The juvenile snails with the size of 1-2 cm, which are suitable for proliferation, release or artificial cultivation, are provided, and the present application provides a solid reference for the breeding of Patella pellucida.

Description

Technical Field

[0001] This invention belongs to the field of large-scale seedling cultivation technology for shellfish, and more specifically, relates to a method for large-scale seedling cultivation of the snail *Pterocarya stenoptera*. Background Technology

[0002] The red-mouthed snail (Strombus luhuanus), also known as the strawberry snail, gets its name from the orange-red color of the inside of its shell opening. It belongs to the class Gastropoda, order Mesogastropoda, family Strombidea, and genus Strombus. Red-mouthed snails live in the intertidal zone to shallow sea sand, gravel, or coral reefs.

[0003] In recent years, due to factors such as the decline of natural populations, the deterioration of the coastal ecological environment, habitat destruction, and overfishing by humans, the number of whelks has dropped sharply, seriously threatening their survival and reproduction.

[0004] To protect biodiversity and ensure the population size of the common prawn snail, it is imperative to develop snail seedling cultivation techniques, which is of great significance for snail resource restoration, restocking, and artificial breeding. Although many scholars have explored snail seedling cultivation, no reports of successfully cultivating snail seedlings have been found so far. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, this invention proposes a method for large-scale seedling cultivation of *Pterocarya stenoptera*.

[0006] A second objective of this invention is to provide an application of the above-described method.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] A method for large-scale seedling cultivation of *Gnaphalium affine* includes the following steps:

[0009] (1) Cultivation of algae feed: After cleaning and disinfecting the algae attachment plate, immerse it in the flowing water pool for algae feeding 2 to 3 times. When the algae attachment plate turns dark brown, let it stand for cultivation and use.

[0010] The algae-attachment operation is as follows: place the algae attachment plate in running water for 2 to 3 days, and then rinse the algae attachment plate with seawater;

[0011] (2) Construction of a flowing water aquaculture pond: Select an aquaculture pond with moderate light, clean and disinfect it, and immerse a 300-mesh screen bag with an open top into the aquaculture pond. Set up a flowing water system and a nutrient supply system inside the screen bag to create an independent aquaculture water environment inside the screen bag.

[0012] (3) Cultivation of planktonic larvae of snails: Place the egg bags of snails on a basket with an 80-mesh screen in advance, so that the basket floats in the cultivation water inside the screen bag. Then cover the entire cultivation pond with a canvas for shading cultivation. After 1 to 2 days, planktonic larvae appear on the cultivation water inside the screen bag. Start feeding the planktonic larvae with live food algae until they develop into the late stage of vegetative larvae, and wait for attachment metamorphosis.

[0013] (4) Snail seedling attachment metamorphosis: During the snail seedling metamorphosis attachment period, open the light-blocking canvas, stop feeding live food algae, string together 4 to 5 algae attachment plates prepared in step (1) with rope, and hang them in the screen bag culture water of the snail seedling planktonic larvae that have developed to the late stage of vesicle larvae obtained in step (3) until snail seedlings of 1 to 3 mm in size can be seen attached to the algae attachment plates with the naked eye.

[0014] (5) Snail seedling rearing: The algae attachment plates with attached snail seedlings are disassembled into pieces, laid flat at the bottom of the breeding pond, fed with bait, and continued to be reared for 60 to 90 days. They will grow into juvenile snails with a size of 10 to 18 mm. At this time, the juvenile snails can be separated and reared in the breeding pond.

[0015] Currently, only a few scholars have reported on the growth of *Pterocarya stenoptera* seedlings in the wild. Although some scholars have explored artificial cultivation of *Pterocarya stenoptera* seedlings, the longest survival time for planktonic larvae is only 17 days, and they may not even develop to the attachment metamorphosis stage. Therefore, there are no successful cases of *Pterocarya stenoptera* seedling cultivation. Preliminary exploratory experiments have found that the bottlenecks in *Pterocarya stenoptera* seedling cultivation are three aspects: the rapid growth of harmful algae and protozoa causing the death of planktonic larvae, low survival rate of attachment metamorphosis, and high water quality requirements.

[0016] 1. To inhibit the rapid growth of harmful algae and protozoa, this invention utilizes the characteristic that algae and protozoa are difficult to grow in a dark environment. The breeding pond is completely shaded to cultivate planktonic larvae of snails, effectively solving the problem of snail mortality caused by the rapid growth of harmful organisms.

[0017] 2. Unlike scraping-feeding mollusks such as whelks and abalone, *Pterocarya spp.* (also known as viper snails) prefer to feed on firmly attached diatoms. However, the membrane-based algae-accepting method used for abalone cannot effectively capture firmly attached diatoms, and the buoyancy of the membrane is also unfavorable for the attachment of *Pterocarya spp.* seedlings. Therefore, this invention employs an attachment plate algae-accepting method, which removes loosely attached algae through multiple rinsing processes, efficiently capturing a sufficient amount of diatoms and solving the bottleneck problem of low attachment metamorphosis rate.

[0018] 3. Unlike the water-changing culture ponds used for breeding oysters, abalone, scallops, and whelks, whelk seedlings are extremely sensitive to water quality changes, and mass mortality occurs continuously during water changes. Therefore, we adopted a screen-mesh flow-through culture method, which completely solves the problem of abnormal mortality caused by unstable water quality in whelks.

[0019] Preferably, in the above-mentioned method for large-scale seedling cultivation of *Gnaphalium affine*, step (3) of feeding the planktonic larvae with live food algae is as follows:

[0020] S1. Once planktonic larvae appear in the screen bag, start feeding with golden algae feed. Feed once each in the morning, noon and evening, with a density of 10,000 to 20,000 golden algae per milliliter each time. Turn off the water flow system and the nutrient supply system when feeding, and turn them back on 1 hour after feeding.

[0021] S2. After culturing the planktonic larvae for 5 to 10 days, feed them a mixture of golden algae, chamomile, chlorella, and flat algae at a density of 20,000 to 30,000 per milliliter.

[0022] S3. After 20-25 days of rearing, the planktonic larvae can develop into the late vegetative larva stage.

[0023] Preferably, in the above-mentioned method for large-scale seedling cultivation of *Gnaphalium affine*, step (4) involves hanging 2-3 strings of algae attachment plates per cubic meter of water and cultivating in flowing water for 7-10 days.

[0024] Another key issue determining the success of whelk seedling cultivation is the feeding of the juvenile snails. We have successfully discovered that the juvenile snails prefer algae. By feeding them algae such as seaweed and sea lettuce, we have ensured the normal growth and development of the juvenile snails and achieved a high survival rate. This has successfully solved the problem of feeding whelk seedlings and provided a solid foundation for the artificial and large-scale cultivation of whelks.

[0025] Therefore, preferably, in the above-mentioned method for large-scale seedling cultivation of *Ulva spp.*, step (5) involves adding 2-3 pinches of algae food to each corrugated plate to promote the growth of the seedlings. More algae can be added after the seedlings have finished feeding. The algae food is *Ulva prolifera* or *Ulva spp.*

[0026] The present invention also provides the application of the above-mentioned method for large-scale seedling cultivation of *Pterygota esculenta* in the large-scale cultivation of *Pterygota esculenta*.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] Based on literature review and practical aquaculture experience, this invention concludes that the main reasons for seedling failure are high mortality rates during the planktonic and attachment stages, susceptibility of the seedling water to protozoan invasion, and the tendency for harmful algae to proliferate, preventing the seedlings from developing into benthic larvae. This invention overcomes the bottlenecks in *Pelodiscus canaliculata* seedling cultivation by optimizing the seedling environment, improving seedling techniques, and controlling light intensity. It enables large-scale cultivation of *Pelodiscus canaliculata* seedlings, providing juveniles of 1-2 cm in size suitable for release or artificial breeding, thus providing a solid reference for *Pelodiscus canaliculata* propagation. Attached Figure Description

[0029] Figure 1The following is the situation of algae on the corrugated plate after 3 days: (A) Before rinsing, a large amount of viscous debris was attached to the corrugated plate; (B) Under a microscope, the algae on the corrugated plate before rinsing showed a lot of debris; (C) After rinsing, the corrugated plate was clean, with less debris, and was yellowish-brown; (D) Under a microscope, the algae on the corrugated plate after rinsing were evenly distributed and included various types of algae such as rhomboid algae and diatoms.

[0030] Figure 2 The following is the condition of the corrugated plate after 20 days of algae storage; (A) Front view; (B) Back view;

[0031] Figure 3 It is a planktonic larval flow-through aquaculture system; (A) the water inlet outside the screen (long arrow), the water inlet inside the screen (short arrow), and the water flow through the PVC pipe with holes drilled directly above the screen (dashed arrow); (B) the air inlet inside the screen (long arrow);

[0032] Figure 4 It is the hatching and rearing of planktonic larvae; (A) A basket containing egg bags floats on the water surface (long arrow), and the eggs will swim into the screen after hatching; (B) The snail seedling rearing pond is shaded by a canvas throughout the rearing process;

[0033] Figure 5 These are egg sacs of the snail *Pterocarya spp.*; (A) Egg sacs laid next to the parent snail (long arrow), clustered together and fluffy; (B) Egg sacs detached from the spawning pond; (C) A single egg sac (long arrow), filamentous, pale yellow, about 1 mm in diameter; (D) Larva inside the egg sac (long arrow), about 150 micrometers in diameter, in the blastocyst stage.

[0034] Figure 6 This is the development process of the snail during its 1-4 day incubation period; (A) On the first day, eye spots appear, yolk sac (arrow) appears, and it begins to rotate; (B) On the second day, its body begins to twist; (C) On the third day, it begins to feed, and food appears in its stomach (arrow); (D) On the fourth day, the larva begins to swim upright.

[0035] Figure 7 This is the 5-8 day development process of the larvae of the snail *Pterocarya stenoptera*; (A) On the fifth day, tentacles appear on the larvae (arrow); (B) On the sixth day, the larvae's internal organs (arrow) are clearly visible, including the hepatopancreas, digestive glands, etc.; (C) On the seventh day, the larvae's body whorl is obvious (arrow); (D) On the eighth day, the larvae's facial disc (arrow) further develops, becoming four-lobed, and can retract into the body whorl.

[0036] Figure 8This is the 9-16 day development process of the larvae of the finless porpoise; (A) On the ninth day, the larvae's shell is obvious, and the vesicle can be completely retracted into the shell; (B) On the eleventh day, the larvae have obvious tentacles (arrow), and the vesicle extends out a large area; (C) On the fifteenth day, the larvae are cotton-like (arrow), which can be seen with the naked eye; (D) On the sixteenth day, the larvae develop a lingula (arrow), and the vesicle is hexagonal;

[0037] Figure 9 This is the 17-22 day development process of the larvae of the snail *Pterocarya stenoptera*; (A) On the seventeenth day, the larvae develop abdominal feet (arrow) and long, thin tentacles (dummy arrow); (B) On the eighteenth day, the larvae develop operculum (arrow); (C) On the twentieth day, most larvae are fully developed and the cilia have basically disappeared; (D) On the twenty-second day, the larvae enter the crawling stage and prepare to attach.

[0038] Figure 10 This is the development process of juvenile snails; (A) Nine days after attachment, the juvenile snails (arrows) have visible tongues and tentacles; (B) Nineteen days after attachment, the juvenile snails (arrows) attach to the rocks and scrape algae from the rocks; (C) Nineteen days after attachment, the juvenile snails' shells are about 4 mm high; (D) Thirty-nine days after attachment, some juvenile snails have detached; (E) Thirty-nine days after attachment, the juvenile snails' shells are about 13 mm high; (F) Sixty-nine days after attachment, the juvenile snails' shells are about 17 mm high. Detailed Implementation

[0039] To better illustrate the purpose, technical solution, and advantages of this invention, the invention will be further described below with reference to specific drawings and embodiments. Unless otherwise specified, the experimental methods used in the embodiments are conventional methods, and the materials and reagents used are commercially available unless otherwise specified.

[0040] Example 1

[0041] I. Cultivation of Algae Feed

[0042] Corrugated board for harboring benthic diatoms (algae): Clean the corrugated board thoroughly, then disinfect it with strong chlorine (concentration 20-40 g / m³). 3 or potassium permanganate (concentration 5-15 g / m³) 3 Soak for 30-60 minutes before use.

[0043] Immerse the corrugated board in a well-lit, flowing water tank with a water depth of 0.5–1 m. After 2–3 days, check the algae accumulation on the corrugated board. Figure 1 A and Figure 1As shown in Figure B, in the first 2-3 days, a large amount of viscous debris adhered to the corrugated board, and many protozoa roamed the surface. At this time, the corrugated board needed to be rinsed with seawater to wash away the impurities and protozoa, leaving the firmly attached diatoms as algae. The board was then left out of water for 2-3 hours to allow the protozoa to dry out and die. After treatment, the board was noticeably cleaner, yellowish-brown in color, and the algae were firmly attached. Microscopic observation revealed that the algae were evenly distributed and varied, including rice-grain-shaped rhomboid algae and chain-bead-like seaweed algae. Figure 1 C, D).

[0044] To ensure a sufficient supply of algae, the rinsed corrugated plates are immersed again in a flowing water tank for further cultivation. This process is repeated 2-3 times, or even more, involving multiple cultivation and rinsing steps. After about 20 days, a sufficient quantity and high purity of algae can be obtained. At this point, the corrugated plates are dark brown and approximately 1 mm thick. Figure 2 ).

[0045] Add diatom culture nutrients to the algae cultivation pond, specifically 15g urea, 5g potassium dihydrogen phosphate, 0.05g ferric citrate, and 10g sodium silicate per cubic meter of seawater. Maintain appropriate lighting, a water depth of 0.5–1m, and oxygenation in the algae cultivation pond, allowing the dark brown corrugated plates to settle and be ready for use.

[0046] II. Construction of Flow-through Aquaculture System

[0047] Choose a well-lit cement pool (5-8m long x 2-4m wide), clean the bottom and walls thoroughly, and apply strong chlorine solution (20-40g / m³). 3 or potassium permanganate (concentration 5-15 g / m³) 3 Disinfect overnight.

[0048] A custom-made 3m x 3m, 300-mesh (approximately 50μm aperture) screen is fixed in the middle of the aquaculture pond using thick bamboo poles. A 15mm diameter PVC pipe is then constructed, running longitudinally across the long side of the pond. Perforations are drilled at 10cm intervals on the PVC pipe above the screen. One end of the PVC pipe is connected to a water inlet, and a valve is installed at the other end, forming a simple water flow system. Figure 3 A). Place air stones evenly above the bottom of the sieve, about 30cm from the bottom, to form an oxygen supply system. Figure 3 B). Open the inlet of the aquaculture pond, with an inflow rate of 3-10 L / min, and control the water depth at the outlet to 1.2 m, thus forming a water flow system within the aquaculture pond. Open the inlet of the PVC pipe, with an inflow rate of 2-5 L / min, and close the valve at the other end, thus forming a water flow system within the screen. Turn on the oxygen supply system and maintain a moderate air output from the aeration stones, thus forming an oxygen supply system within the screen.

[0049] III. Egg Bag

[0050] Egg sacs of the *Pterocarya spp.* are typically laid in pairs or groups of 3-5 parent snails, adhering together in loose, clustered piles. Their color is similar to that of their surroundings; egg sacs laid in sand tend to be brownish-yellow. The egg sacs often form a continuous sheet, approximately 2-5 cm in length. Individual egg sacs are filamentous, pale yellow, about 1 mm in diameter, and 3-10 cm in length. The egg sacs contain numerous blastocyst or single-rotation larvae, which can be seen rotating within the membrane before rupture. Figure 5 ).

[0051] IV. Planktonic Larvae Culture of Snail Seedlings

[0052] Place the egg bags of *Pterocarya spp.* on baskets pre-inserted with an 80-mesh sieve and secured with foam around the edges. Then, float the baskets in a flowing water culture pond, placing 200-300 egg bags in each pond. To avoid or delay the growth of harmful algae and protozoa, cover the entire flowing water culture pond with tarpaulin for shade throughout the entire process of raising the planktonic larvae. Figure 4 B). After 1-2 days, the fertilized eggs mature within the egg sac, break through the membrane, and form planktonic larvae. Once the planktonic larvae appear in the sieve, begin feeding with golden algae feed, three times a day (morning, noon, and evening), at a density of 10,000-20,000 algae per ml each time. Turn off the water flow and aeration equipment during feeding, and turn them back on 1 hour later. After 5-10 days of planktonic larval rearing, feed a mixture of golden algae, Chaetoceros, Chlorella, and Platycladus (in any proportion), at a density of 20,000-30,000 algae per ml. After 20-25 days of rearing, the planktonic larvae will develop into the late vegetative larval stage, awaiting attachment metamorphosis.

[0053] The morphological changes during the planktonic larval stage are as follows:

[0054] Day 1: The larvae emerge from the egg sac and swim in a rotating motion, approximately 150 μm in diameter. Eye spots appear, the head has two tufts of cilia, and the yolk sac is located at the posterior end of the body. Figure 6 A).

[0055] Day 2: The larvae begin to develop in size and start to twist slightly, primarily using rotational movements. Figure 6 B).

[0056] Day 3: The larvae begin to feed on algae, develop digestive glands, and their stomachs clearly contain food. Figure 6 C).

[0057] Day 4: The larvae begin to transition from rotating to straight swimming; the preoral organs continue to develop, and distinct ciliary rings appear. Figure 6 D).

[0058] Day 5: The larva is about 200 μm in diameter, tentacles begin to appear, and the body becomes more twisted. Figure 7 A).

[0059] Day 6: The internal organs of the larvae develop further, with digestive glands, liver, and pancreas becoming more prominent. Figure 7 B).

[0060] Day 7: The larvae have already developed the rudiments of an adult snail, with distinct body whorls and a relatively short spire. Figure 7 C).

[0061] Day 8: The larval vesicles develop further, becoming four-lobed, and can retract into the body whorl. Figure 7 D).

[0062] Day 9: The larva is about 300 μm long, the shell is distinct, the body whorl is enlarged, and the facial disc can completely retract almost into the shell. Figure 8 A).

[0063] Day 11: The tentacles of the larvae are clearly visible, and most of them swim and live in the middle and lower water layers. Figure 8 B).

[0064] Day 15: The larvae are approximately 400 μm in size, appearing cotton-like and visible to the naked eye. Figure 8 C).

[0065] Day 16: The larvae develop a mouth and tongue, and begin to transition from filter feeding to scraping algae. Their vegetative discs become hexagonal. Figure 8 D).

[0066] Day 17: The larvae develop abdominal feet, tentacles become thinner and longer, the shell is fully developed, and the apex is distinct. Figure 9 A).

[0067] Day 18: The larvae develop an operculum, their abdominal feet thicken, and their contractile ability increases. Figure 9 B).

[0068] Day 20: The facial disc of the juvenile begins to degenerate, and the cilia almost disappear. Figure 9 C).

[0069] Day 22: The larvae are approximately 500 μm in size, entering the crawling stage. Their abdominal legs are fully developed, preparing for attachment. Figure 9 D).

[0070] V. Snail seedling attachment metamorphosis

[0071] During the metamorphosis and attachment of the snail larvae, open the shading tarpaulin covering the culture pond. Stop feeding live algae. String together 4-5 corrugated plates that have been pre-treated with algae for more than 20 days, and then suspend them in the culture pond for the planktonic larvae that have developed to the late vegetative stage. Hang 2-3 strings of corrugated plates per cubic meter of water. After 7-10 days of flowing water culture, snail larvae of 1-3 mm in size can be seen attached to the corrugated plates.

[0072] VI. Snail Seedling Rearing

[0073] Disassemble the corrugated plates with attached snail larvae into pieces and lay them flat at the bottom of the rearing pond. To promote snail growth, add 2-3 pinches of algae such as seaweed or sea lettuce to each piece of corrugated plate. Continue adding algae after the snails have finished feeding. Continue rearing in the pond for 60-90 days until the snails grow to 10-18mm in size. At this point, the snails can be separated from the corrugated plates and transferred to the rearing pond. The juvenile snails mainly feed on algae on the bottom or walls of the pond. When food is scarce, seaweed, sea lettuce, or sea lettuce can be added to the pond.

[0074] The morphology of the juvenile snails is observed as follows:

[0075] Day 30 (9 days after attachment): The juvenile snail's shell is about 2mm high, fully developed, with clearly visible mouth, tentacles, and other organs, scraping and feeding on diatoms on the corrugated plate. Figure 10 A).

[0076] Day 40 (19 days after attachment): The juvenile snail's shell is about 4mm high. It likes to attach to hard materials such as rocks and sand. It is very responsive and will immediately retract when startled. It has a strong ability to turn over. Figure 10 B, C).

[0077] Day 60 (39 days after attachment): The juvenile snail's shell is about 13mm high. Its diet is similar to that of the adult snail, and it can feed on larger algae such as seaweed and sea lettuce. The shell is thicker, the body color turns brown, the body whorl hardens, and the spire becomes more prominent. Figure 10 D, E).

[0078] Day 90 (69 days after attachment): The juvenile snail's shell height is approximately 17mm. Growth and transformation are slower than before, the shell becomes thicker, and its mobility is stronger and wider. Figure 10 F).

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for cultivating hatchlings of the species Morula conronata on a large scale, characterized by, It comprises the following steps: (1) culture of algal bait: after the algal attachment board is washed and disinfected, it is immersed in a flowing water pool for 2-3 times of algal collection operation, and when the algal attachment board presents a dark brown color, it is placed for culture; the algal collection operation is that the algal attachment board is placed in flowing water for 2-3 days, and then the algal attachment board is washed with seawater; (2) construction of a flowing water culture pond: a 300-mesh screen bag with an open top is immersed in the culture pond after the culture pond is selected and washed and disinfected, a flowing water system and an oxygen supply system are arranged in the screen bag, so that an independent culture water environment is formed in the screen bag; (3) culture of planktonic larvae of snail fry: the egg bag of the snail fry is placed on a basket with a 80-mesh screen in advance, so that the basket floats in the culture water in the screen bag, and then the whole culture pond is covered with a canvas for shading culture, after 1-2 days, planktonic larvae appear in the culture water in the screen bag, and then live bait algae are fed to the planktonic larvae until the larvae develop to the late trochophore stage, and then metamorphosis is waited for; in order to avoid or delay the growth of harmful algae and protozoa, the whole flowing water culture pond is covered with a canvas for shading during the whole process of culture of the planktonic larvae; (4) metamorphosis of the snail fry: during the metamorphosis of the snail fry, the shading canvas is opened, the feeding of the live bait algae is stopped, and 4-5 pieces of the algal attachment board prepared in step (1) are hung in the screen bag culture water of the snail fry developed to the late trochophore stage obtained in step (3) by a rope, and the culture is continued until the snail fry of 1-3 mm in size can be seen attached to the algal attachment board; (5) culture of the snail fry: the algal attachment board with the attached snail fry is taken out and laid on the bottom of the culture pond, and bait is fed, and the culture is continued for 60-90 days, so that the snail fry grows to 10-18 mm in size, and then the snail fry on the algal attachment board is peeled off and cultured in the culture pond; The operation of feeding the live bait algae to the planktonic larvae in step (3) is as follows: S1, after the planktonic larvae appear in the screen bag, the feeding of the golden algae bait is started, and the golden algae are fed once in the morning, at noon and in the evening, and the density of the golden algae is 10-20 thousand per milliliter each time; during the feeding, the flowing water system and the oxygen supply system are closed, and after 1 hour, the flowing water system and the oxygen supply system are opened again; S2, after the culture of the planktonic larvae for 5-10 days, the golden algae, the chrysophyta, the chlorella and the tetraselmis are mixed and fed, and the density is 20-30 thousand per milliliter; S3, after the culture of the planktonic larvae for 20-25 days, the planktonic larvae develop to the late trochophore stage; In step (5), 2-3 scoops of algal food are added to each piece of the algal attachment board, and after the feeding is completed, the feeding can be continued.

2. The method according to claim 1, wherein In step (4), 2-3 strings of the algal attachment board are hung in each cubic water body, and the flowing water culture is continued for 7-10 days.

3. The method according to claim 1, wherein the method is characterized by, The algal food is haematococcus, enteromorpha.

4. Application of the snail fry large-scale breeding method according to any one of claims 1-3 in large-scale breeding of the snail fry.

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