A method for culturing larvae of freshwater croaker and domesticating them to improve the conversion rate of floating feed for juveniles

Abstract

The present invention discloses a method for culturing juvenile Pseudosciaena polyactis and improving the conversion rate of floating feed for juvenile fish during domestication, belonging to the technical field of aquaculture. It includes three parts: pond preparation, juvenile fish cultivation, and juvenile fish domestication. The juvenile fish domestication is divided into four stages: floating frame domestication, sinking frame domestication, artificial slowly sinking bait domestication, and floating feed domestication. This method has strong operability and good practical applicability, can significantly improve the conversion rate of floating bait for juvenile Pseudosciaena polyactis, realize large-scale domestication of fry, and promote the industrial development of Pseudosciaena polyactis aquaculture. Practice shows that the conversion rate of floating feed for Pseudosciaena polyactis can be increased to 80-90%, and after one year of cultivation, the domesticated Pseudosciaena polyactis can reach the market specification of 500-600 g.

Description

Technical Field

[0001] The present invention belongs to the technical field of aquaculture, and particularly relates to a method for culturing juvenile freshwater drum (Aplodinotus grunniens) and improving the conversion rate of floating feed for juvenile fish during the domestication process. Background Art

[0002] Freshwater drum (Aplodinotus grunniens), commonly known as freshwater yellow croaker or freshwater large yellow croaker, belongs to Perciformes and Sciaenidae. It is the most widely distributed warm-water fish in North America and is one of the only two species in the world's 275 Sciaenidae species that live in fresh water throughout their lives. Due to its strong adaptability, fast growth, good meat quality (flakey meat), and no intermuscular spines, and it can feed on formulated feed through artificial domestication, it is suitable for aquaculture in fresh water and brackish water in most parts of China. It is a new and excellent aquaculture variety with good breeding prospects and broad market prospects.

[0003] Foreign researchers have conducted many studies on the natural resources, basic biology, and reproductive biology of freshwater drum. In China, only Zhou Libin et al. have studied the meat content and muscle nutrient components of freshwater drum, Wen Haibo has studied the metamorphosis process of glochidium larvae of Anodonta woodiana parasitizing freshwater drum, the external morphology, internal anatomy, and mitochondrial genome characteristics of juvenile freshwater drum. Given the advantages and breeding prospects of freshwater drum, in 2016, the Freshwater Fisheries Research Center of the Chinese Academy of Fishery Sciences successfully introduced a batch of wild fry of freshwater drum. Through more than three years of artificial domestication and technical research, in 2019, the artificial breeding technology was first broken through globally, and many technical difficulties in artificial induced spawning, fry hatching, and first feeding were solved, laying an important foundation for the large-scale breeding of freshwater large yellow croaker fry and the industrial development of aquaculture in China.

[0004] Freshwater drum is an omnivorous fish with a carnivorous tendency. Since its artificial breeding has not been broken through abroad and the domestication of artificial bait has not been carried out, the domestication of F1 and F2 fry bait is extremely difficult. In addition, freshwater drum is a bottom-dwelling fish and is more accustomed to eating sinking bait. The conversion success rate of using traditional floating feed domestication technology for fish fry is low, resulting in extremely slow growth of freshwater drum, seriously restricting the large-scale aquaculture and popularization process of freshwater drum in China. Summary of the Invention

[0005] In view of the problems existing in the above-mentioned prior art, the present invention provides a method for culturing juvenile freshwater drum and improving the conversion rate of floating feed for juvenile fish during the domestication process.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A method for culturing juvenile freshwater drum, comprising the following steps:

[0008] a. Pond preparation

[0009] Select a pond with a depth of 2.5 - 3.5 m. After pond cleaning and disinfection for 5 - 6 days, inject water to a depth of 0.8 - 1 m. Install a filter net at the water inlet, sprinkle fertilizer paste, and release juvenile fish after 3 - 4 days. Gradually increase the water level to 1.2 - 1.5 m;

[0010] b. Juvenile fish cultivation

[0011] 1) One day before releasing juvenile fish, sprinkle Schizochytrium powder and puffer fish powder in the pond, with a mass ratio of 1:9 and a dosage of 0.8 - 1 kg / mu, and sprinkle it once every 3 days after the juvenile fish are put into the pond;

[0012] 2) After the juvenile fish are put into the pond, sprinkle vitamin C in the pond. When the density of rotifers is relatively low, start cage domestication.

[0013] Furthermore, the fry are stocked in the pond 18 - 19 days after hatching. When stocked, the size of the juvenile fish is 1.3 - 1.6 cm, and the stocking density is 150,000 - 200,000 tails / mu.

[0014] Furthermore, the dosage of vitamin C sprinkled is 200 g / mu·m; the time when the density of rotifers is relatively low is 10 - 12 days after the juvenile fish are put into the pond, and at this time, the size of the juvenile fish is 3.0 - 4.0 cm.

[0015] The present invention also provides a domestication method for improving the conversion rate of floating feed for juvenile fish. When the juvenile fish cultivated by the above cultivation method are cultivated to the juvenile fish stage, they are netted and put into a cage for domestication. The domestication includes four stages: floating frame domestication, sinking frame domestication, artificial slow-sinking bait domestication, and floating feed domestication. Specifically:

[0016] ① Floating frame domestication: Put frozen cladocerans on the floating frame at the domestication point and let them melt slowly. The domestication time is from 7:00 to 11:00 in the morning and from 13:00 to 17:00 in the afternoon, and domesticate for 7 days;

[0017] ② Sinking frame domestication: Mix frozen cladocerans and powdered feed with water, press them into blocks and put them on the sinking frame for domestication. The domestication time is from 7:00 to 9:00 in the morning and from 15:00 to 17:00 in the afternoon, and domesticate for 10 days;

[0018] ③ Artificial slow-sinking bait domestication: Add slow-sinking expanded feed to water to soften it, and manually knead it into flat shapes with a diameter of 1.5 - 2.5 cm for feeding. Feed 10 - 20 grains per minute and feed for 4 hours every day. The domestication time is from 7:00 to 9:00 in the morning and from 15:00 to 17:00 in the afternoon, and domesticate for 7 days;

[0019] ④ Floating feed domestication: Use extruded feed for feeding. The domestication time is 7:00-9:00 in the morning and 15:00-17:00 in the afternoon. The domestication takes 7 days to complete the domestication of the young fish. After the domestication is completed, the fish are placed in the pond and 2-3 feeding points are set up per acre for breeding.

[0020] Furthermore, after the net is pulled, the young fish are placed in a cage with a length, width and height of (6-8) m, (4-5) m and (2-2.5) m, and the cage domestication density is 1200-1500 fish / m 2 The mesh size should be the maximum size that the fish cannot escape, and one feeding point should be set in each cage.

[0021] Furthermore, the floating frame is made of PVC pipe, with a length and width of 60×30 cm, two layers of 10-16 mesh nets are fixed inside, floats are tied to the four corners, and it is fixed to the two frames of the cage with a rope. When feeding, it is 30-40 cm below the water surface.

[0022] Furthermore, the sinking frame is made of stainless steel pipe or iron rod, with a length and width of 60×30 cm, and two layers of 10-16 mesh nets are fixed on the inside and fixed to the frame of the cage with ropes. The depth is 1.8-2m when feeding on the first day, and then rises 0.1-0.2m every day, and is 0.3-0.5m below the water surface on the 10th day.

[0023] Furthermore, during the sinking frame domestication process, the mass ratio of the frozen cladocerans to the powdered feed is (7-3):(3-7), and the protein content of the powdered feed is above 50%.

[0024] Furthermore, the floating feed domestication is to scatter the feed into a 2m×2m square frame made of a PVC pipe, and fix the frame to a net cage or a wooden stake at a feeding point with a rope; the protein content of the puffed feed and the slow-sinking puffed feed is above 48%.

[0025] Furthermore, during the fry domestication process, 1 g / catties of Schizochytrium powder was added to all feeds until the domestication was completed.

[0026] After the net is pulled, the young fish are domesticated in the cage and do not need to be transferred until the domestication is completed and then transferred to the pond.

[0027] Compared with the prior art, the present invention has the following advantages and technical effects:

[0028] The cultivation method and domestication method provided by the present invention can effectively reduce the pollution to the aquaculture water body, observe the feeding situation of the fish more intuitively, accelerate the growth rate of the freshwater totoaba, establish the technical process of commercial fish pond aquaculture, and be beneficial to promote the industrialization development of artificial aquaculture of freshwater totoaba.

[0029] The cultivation method and domestication method provided by the present invention are highly operable and have good practical applicability, enabling large-scale domestication of Pseudosciaena polyactis fry and laying a solid foundation for the industrial development of Pseudosciaena polyactis fry. Practice has shown that the conversion rate of floating feed for Pseudosciaena polyactis can be increased to 80-90%, and after one year of cultivation, the domesticated Pseudosciaena polyactis can reach the market specification of 500-600 g. Detailed Embodiments

[0030] The various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be construed as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0031] It should be understood that the terms used in the present invention are only for describing specific embodiments and are not intended to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0032] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0033] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific embodiments of the present invention specification, which are obvious to those skilled in the art. Other embodiments obtained from the specification of the present invention are obvious to those skilled in the art. The specification and examples of this application are merely exemplary.

[0034] Regarding the use of "comprising", "including", "having", "containing", etc. in this article, they are all open-ended terms, meaning including but not limited to.

[0035] The raw materials used in the embodiments of the present invention are all obtained commercially.

[0036] A method for cultivating Pseudosciaena polyactis juveniles includes the following steps:

[0037] a. Pond preparation

[0038] Choose a pond of 4-10 mu with a depth of 2.5-3.5m. Before stocking the fry, thoroughly clean and disinfect the pond, remove wild fish and other harmful organisms, add water 0.8-1m after cleaning the pond for 5-6 days, add a 100-mesh silk screen to the water inlet to prevent fish and shrimp from entering, sprinkle fertilizer paste (Wuxi Tongwei Biotechnology Co., Ltd., the amount of spraying is based on the recommended amount of the product), put the fry in after 3-4 days, and gradually increase the water level to 1.2-1.5m;

[0039] b. Juvenile fish cultivation

[0040] 1) Sprinkle the pond with Schizochytrium powder and Fugu powder one day before stocking the juveniles, with a mass ratio of 1:9 and a dosage of 0.8-1 kg / mu. Sprinkle once every 3 days after the juveniles are put into the pond;

[0041] 2) After the fry are put into the pond, sprinkle vitamin C throughout the pond at 200g / mu·m to reduce the stress response of the fry during transportation. When the rotifer density is low, start cage training.

[0042] In some preferred embodiments, the fry are stocked into ponds after being cultured for about 18 to 19 days, the size of the fry is about 1.3 to 1.6 cm when they are stocked into ponds, and the stocking density is 150,000 to 200,000 per mu.

[0043] In some preferred embodiments, the density of rotifers and cladocerans is low 10 to 12 days after the juveniles are put into the pond. At this time, the size of the juveniles is 3.0 to 4.0 cm, and cage culture begins.

[0044] The present invention also provides a method for improving the feeding rate of floating feed for young fish. When the young fish obtained by the cultivation method are cultivated to the young fish stage, a net is pulled and put into a net cage for domestication. The domestication includes four stages: floating frame domestication, sinking frame domestication, artificial slow-sinking bait domestication, and floating feed domestication, which are specifically:

[0045] ① Floating frame culture: Frozen cladocerans (about 20×30×20 cm) were placed on floating frames at the culture point and slowly thawed. The culture time was 7:00-11:00 in the morning and 13:00-17:00 in the afternoon, and the culture lasted for 7 days.

[0046] ② Frame taming: Frozen cladocerans and powdered feed are mixed with water and pressed into blocks (about 20×30×20cm) and placed on a frame for taming. The taming time is 7:00-9:00 in the morning and 15:00-17:00 in the afternoon, and the taming lasts for 10 days.

[0047] ③ Artificial slow-sinking feed taming: slow-sinking puffed feed is added to water to soften, and then kneaded into a flat shape with a diameter of 1.5-2.5 cm and fed to the fish. 10-20 pellets are fed per minute for 4 hours a day. The taming time is 7:00-9:00 in the morning and 15:00-17:00 in the afternoon, and the taming time is 7 days.

[0048] ④ Floating feed domestication: Use extruded feed for feeding. The domestication time is 7:00-9:00 in the morning and 15:00-17:00 in the afternoon. The domestication takes 7 days to complete the domestication of the young fish. After the domestication is completed, the fish are placed in the pond and 2-3 feeding points are set up per acre for breeding.

[0049] In some preferred embodiments, after the net is pulled, the young fish are placed in a cage with a length, width and height of (6-8) m, (4-5) m and (2-2.5) m, and the cage domestication density is 1200-1500 fish / m 2 The mesh size should be the maximum size that the fish cannot escape, and one feeding point should be set in each cage.

[0050] In some preferred embodiments, the floating frame is made of PVC pipe, with a length and width of 60×30 cm, two layers of 10-16 mesh nets are fixed on the inside, floats are tied to the four corners, and it is fixed to the two frames of the cage with a rope. When feeding, it is about 30-40 cm below the water surface.

[0051] In some preferred embodiments, the sinking frame is made of stainless steel pipe or iron rod, with a length and width of 60×30 cm, and two layers of 10-16 mesh nets are fixed on the inside and fixed to the frame of the cage with ropes. The depth is 1.8-2 m when feeding on the first day, and then rises by 0.1-0.2 m every day, and is 0.3-0.5 m below the water surface on the 10th day.

[0052] In some preferred embodiments, during the sinking frame domestication process, the mass ratio of the frozen cladocerans to the powdered feed is (7-3):(3-7), preferably 7:3, 5:5, 3:7; the protein content of the powdered feed is above 50%.

[0053] In some preferred embodiments, the floating feed domestication is to scatter the feed into a 2m×2m square frame made of a PVC pipe, and fix the frame to a net cage or a wooden stake at the feeding point with a rope; the protein content of the puffed feed and the slow-sinking puffed feed is above 48%.

[0054] In some preferred embodiments, during the fry domestication process, 1 g / catties of Schizochytrium powder is added to all feeds until the domestication is completed.

[0055] The following examples serve as further illustrations of the technical solutions of the present invention.

[0056] Example 1

[0057] Step 1, select a 5 mu pond with a depth of 2.5m. Before stocking the fry, thoroughly clean and disinfect the pond on April 19, remove wild fish and other harmful organisms, fill the pond with water about 1m on April 25, add a 100-mesh silk screen to the water inlet to prevent fish and shrimp from entering, expose the water to the sun for 4 days, sprinkle fertilizer paste on the whole pond on April 29, sprinkle 5kg of a mixture of schizochytrid powder and pufferfish powder (mass ratio of 1:9) on May 1, and gradually increase the water level to 1.3m;

[0058] Step 2: In the early morning of May 2, the fry (about 1.4 cm in size) were moved into the domestication pond with water by using a nylon bag oxygenation method. The stocking density was about 200,000 fry / mu, and the water temperature was about 20°C. After stocking, 1 kg of vitamin C was sprinkled throughout the pond. During this period, a mixture of schizochytrid powder and pufferfish powder was sprinkled once every 3 days. After 11 days of cultivation, the fish were put into the cage for domestication.

[0059] Step 3: Cage size 6×5×2.5m, stocking density 1200 fish / m 2 , the mesh diameter is 0.2cm, and a feeding point is set in each cage;

[0060] ①. Floating frame culture: Frozen cladocerans (purchased from the market, in block form, about 30×20×20 cm in length, width and height, just keep them on the floating frame during the culture period) are placed on a 60×30 cm floating frame, with floats tied to the four corners. When feeding, the frame is about 40 cm below the water surface. The culture period is 7:00-11:00 a.m. and 13:00-17:00 p.m., and the culture period is 7 days.

[0061] ②, sinking frame method: frozen cladocerans and powdered feed (protein content of 50%) are mixed in a mass ratio of 7:3, 5:5, and 3:7, and an appropriate amount of water is added to mix and feed into blocks (about 20×30×20cm) (the process of setting the raw material ratio is that the frozen cladocerans gradually decrease and the powdered feed gradually increases). The domestication time is 7:00-9:00 in the morning and 15:00-17:00 in the afternoon. The domestication is 10 days (keep it on the sinking frame all the time). The feeding depth on the first day is about 1.8m, and then it is raised by 0.1-0.2m every day. On the 10th day, it is 0.4m below the water surface;

[0062] ③. Artificial slow-sinking feed taming: slow-sinking puffed feed (protein content of 48%) is softened by adding appropriate amount of water (adding water to make it flat) and then artificially kneaded into flat shape before feeding. Feed 10-20 grains per minute (each grain is about 1-1.5cm in diameter, and the total feeding amount is about 2% of the fish body weight). Feed for 4 hours a day. The taming time is 7:00-9:00 in the morning and 15:00-17:00 in the afternoon. The taming time is 7 days.

[0063] ④. Floating feed domestication: Use extruded feed for feeding (the amount is about 3% of the fish body weight, with a protein content of 48%). Sprinkle the feed into a 2m×2m square frame made of PVC pipe, and use ropes to fix the frame to the net cage or the wooden stakes at the feeding point. The domestication time is 7:00-9:00 in the morning and 15:00-17:00 in the afternoon. The domestication takes 7 days to complete the domestication of the young fish. After the domestication is completed, the fish are placed in the pond and 3 feeding points are set up per acre for breeding.

[0064] All feeds used in the domestication process were supplemented with Schizochytrium at 1 g / catties.

[0065] After one year of breeding, the success rate of freshwater drum fish switching to other foods reached 87%, and the weight of successfully domesticated freshwater drum fish was between 500 and 600 grams.

[0066] Example 2

[0067] Step 1, select a 4 mu pond with a depth of 3.5m. Before stocking the fry, thoroughly clean and disinfect the pond on May 20 to remove wild fish and other harmful organisms. On May 26, fill the pond with 0.8m of water, add a 100-mesh silk screen to the water inlet to prevent the entry of fish and shrimp, and expose the water to the sun for 4 days. On May 30, sprinkle fertilizer paste all over the pond. On June 3, sprinkle 4kg of a mixture of schizochytrid powder and pufferfish powder (mass ratio of 1:9) all over the pond, and gradually increase the water level to 1.2m.

[0068] Step 2: In the early morning of June 4, the fry (about 1.5 cm in size) were moved into the domestication pond with water by using a nylon bag oxygenation method. The stocking density was about 200,000 fry / mu, and the water temperature was about 20°C. After stocking, 0.64 kg of vitamin C was sprinkled throughout the pond. During this period, a mixture of schizochytrid powder and pufferfish powder was sprinkled once every 3 days. After 11 days of cultivation, the fish were put into the cage for domestication.

[0069] Step 3: Cage size 6×4×2.5m, stocking density 1400 fish / m 2 , the mesh diameter is 0.2cm, and a feeding point is set in each cage;

[0070] ① Floating frame culture: Frozen cladocerans are placed on a 60×30 cm floating frame with floats tied to the four corners. When feeding, the frame is about 40 cm below the water surface. The culture time is 7:00-11:00 in the morning and 13:00-17:00 in the afternoon, and the culture period is 7 days.

[0071] ②, sinking frame method: frozen cladocerans and powdered feed (protein content of 50%) are mixed in a mass ratio of 7:3, 5:5, and 3:7, and water is added to mix and feed into blocks (about 20×30×20cm). The domestication time is 7:00-9:00 in the morning and 15:00-17:00 in the afternoon. The domestication time is 10 days. The feeding depth on the first day is about 1.8m, and then it is raised by 0.1-0.2m every day. On the 10th day, it is 0.4m below the water surface;

[0072] ③. Domestication with artificial slow-sinking feed: add appropriate amount of water to slow-sinking puffed feed (protein content of 48%) to soften it, and then manually knead it into a flat shape before feeding. Feed 10 to 20 grains per minute for 4 hours a day. The domestication time is 7:00 to 9:00 in the morning and 15:00 to 17:00 in the afternoon. The domestication time is 7 days;

[0073] ④. Floating feed domestication: All extruded feed is used for feeding (protein content is 48%). The feed is spread into a 2m×2m square frame made of PVC pipe, and the frame is fixed to the net cage or the wooden stake at the feeding point with a rope. The domestication time is 7:00-9:00 in the morning and 15:00-17:00 in the afternoon. The domestication is 7 days to complete the domestication of the young fish. After the domestication is completed, the fish are put into the pond and 3 feeding points are set up per acre for breeding.

[0074] All feeds used in the domestication process were supplemented with Schizochytrium at 1 g / catties.

[0075] After one year of breeding, the success rate of freshwater stonefish switching to other foods reached 89%, and the weight of successfully domesticated freshwater stonefish was between 500 and 600 grams.

[0076] Comparative Example 1

[0077] Step 1: Choose a 5-mu pond with a depth of 2.5 meters. Before stocking the fry, thoroughly clean and disinfect the pond on April 19 to remove wild fish and other harmful organisms. On April 25, fill the pond with about 1m of water, add a 100-mesh silk screen to the water inlet to prevent fish and shrimp from entering, and expose the water to the sun for 4 days. On April 29, sprinkle fertilizer paste all over the pond and gradually increase the water level to 1.3m;

[0078] Step 2: In the early morning of May 2, the fry (about 1.4 cm in size) were moved into the domestication pond with water using a nylon bag oxygenation method. The stocking density was about 200,000 fry / mu, and the water temperature was about 20°C. After stocking, 1 kg of vitamin C was sprinkled throughout the pond. After 11 days of cultivation, powder feed domestication began;

[0079] Step 3: Every day from 7:00 to 11:00 in the morning and from 13:00 to 17:00 in the afternoon, evenly spread pufferfish powdered feed (the total feeding amount is about 2% of the fish body weight) on the edge of the pond. After 2 weeks of domestication, set up 3 feeding points per mu, use slow-sinking expanded feed (protein content of 48%) to soften with water and knead it into a flat shape manually for 1 week, then sprinkle the floating feed into a 2m×2m square frame made of PVC pipe, and fix the frame to the wooden stake at the feeding point with a rope. The domestication time is from 7:00 to 9:00 in the morning and from 15:00 to 17:00 in the afternoon. The domestication process is completed after 7 days of domestication;

[0080] Step 4: Slowly add water until the pond water level reaches 2.5 meters and feed approximately 3-4% of the fish body weight every day.

[0081] After one year of breeding, the success rate of freshwater drum switching to other foods reached 4.5%, and the weight of successfully domesticated freshwater drum was 400-500g.

[0082] Comparative Example 2

[0083] Step 1: Select a 4-mu pond with a depth of 3.5m. Before stocking the fry, thoroughly clean and disinfect the pond on May 20 to remove wild fish and other harmful organisms. On May 26, fill the pond with 0.8m of water, add a 100-mesh silk screen to the water inlet to prevent fish and shrimp from entering, and expose the water to the sun for 4 days. On May 30, sprinkle fertilizer paste all over the pond, sprinkle soybean milk every 3 days, and gradually increase the water level to 1.2m;

[0084] Step 2: In the early morning of June 4, the fry (about 1.5 cm in size) were moved into the domestication pond with water using a nylon bag oxygenation method. The stocking density was about 200,000 fry / mu, and the water temperature was about 20°C. After stocking, 0.64 kg of vitamin C was sprinkled throughout the pond. After 8 days of cultivation, the fish were put into the cage for domestication.

[0085] Step 3: Cage size 6×4×2.5m, stocking density 1200 fish / m 2 The mesh diameter is 0.2 cm, and a feeding point is set in each cage; powdered feed (about 1% of the fish body weight) is sprinkled on the cage for 10 days of domestication, and extruded feed (the amount is 2% of the fish body weight, the protein content is 48%) is used for domestication for 7 days. The domestication time is 7:00-9:00 in the morning and 15:00-17:00 in the afternoon. After the domestication, the fish are put into the pond and 3 feeding points are set per acre for breeding.

[0086] After one year of breeding, the success rate of freshwater drum fish switching to other foods reached 3.2%, and the weight of successfully domesticated freshwater drum fish was 400-500g.

[0087] The above are only the preferred specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present application should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A domestication method for improving the conversion rate of floating feed for juvenile fish, characterized in that, When the juvenile fish cultivated by the juvenile fish cultivation method of Johnius belangerii are cultivated to the juvenile fish stage, they are pulled into the net cage for domestication by netting. The domestication includes four stages: floating frame domestication, sinking frame domestication, artificial slow-sinking bait domestication, and floating feed domestication. Specifically: ① Floating frame domestication: Put frozen cladocerans on the floating frame at the domestication point and let them melt slowly. The domestication time is from 7:00 to 11:00 in the morning and from 13:00 to 17:00 in the afternoon, and domesticate for 7 days; ② Sinking frame domestication: Mix frozen cladocerans and powdered feed with water, press them into blocks and put them on the sinking frame for domestication. The domestication time is from 7:00 to 9:00 in the morning and from 15:00 to 17:00 in the afternoon, and domesticate for 10 days; ③ Artificial slow-sinking bait domestication: Soften the slow-sinking expanded feed by adding water, manually knead it into a flat shape with a diameter of 1.5 - 2.5 cm and feed it. Feed 10 - 20 grains per minute, feed for 4 hours every day. The domestication time is from 7:00 to 9:00 in the morning and from 15:00 to 17:00 in the afternoon, and domesticate for 7 days; ④ Floating feed domestication: Use expanded feed for feeding. The domestication time is from 7:00 to 9:00 in the morning and from 15:00 to 17:00 in the afternoon, and domesticate for 7 days to complete the domestication of juvenile fish. After the domestication is over, put the fish into the pond, and set 2 - 3 feeding points per mu for breeding; The juvenile fish cultivation method of Johnius belangerii includes the following steps: a. Pond preparation Select a pond with a depth of 2.5 - 3.5 m, clean and disinfect the pond, inject water 0.8 - 1 m after 5 - 6 days, install a filter net at the water inlet, sprinkle fertilizer paste, and put juvenile fish after 3 - 4 days, and gradually increase the water level to 1.2 - 1.5 m; b. Juvenile fish cultivation 1) One day before the release of juvenile fish, sprinkle Schizochytrium sp. powder and puffer fish powder on the pond, with a mass ratio of 1:9 and a dosage of 0.8 - 1 kg / mu, and sprinkle it once every 3 days after the juvenile fish are put into the pond; 2) After the juvenile fish are put into the pond, sprinkle vitamin C in the pond. When the density of rotifers is relatively low, start net cage domestication.

2. The domestication method for improving the conversion rate of floating feed for juvenile fish according to claim 1, characterized in that, The fry are stocked in the pond 18 - 19 days after cultivation. When stocked, the specifications of the juvenile fish are 1.3 - 1.6 cm, and the stocking density is 150,000 - 200,000 tails / mu.

3. The domestication method for improving the conversion rate of floating feed for juvenile fish according to claim 1, characterized in that, The dosage of vitamin C sprinkled is 200 g / mu·m; when the density of rotifers is relatively low, it is 10 - 12 days after the juvenile fish are put into the pond, and at this time, the specifications of the juvenile fish are 3.0 - 4.0 cm.

4. The domestication method for improving the conversion rate of floating feed for juvenile fish according to claim 1, characterized in that, After setting the net, put the juvenile fish into a net cage with a length, width and height of 6 - 8m, 4 - 5m, and 2 - 2.5m respectively. The domestication density of the net cage is 1200 - 1500 fish / m 2 , and the mesh size should be the largest size that the fish cannot escape through. One feeding point is set in each net cage.

5. The domestication method for improving the conversion rate of floating feed for juvenile fish according to claim 1, characterized in that, The material of the floating frame is PVC pipe, with a length and width of 60×30 cm, and two layers of meshes with apertures of 10 - 16 meshes are fixed inside. Floats are tied to the four corners and fixed to the two side frames of the net cage with a rope, and it is 30 - 40 cm below the water surface during feeding.

6. The domestication method for improving the conversion rate of floating feed for juvenile fish according to claim 1, characterized in that, The sinking frame is made of stainless steel pipes or iron rods, with a length and width of 60×30 cm. Two layers of nets with a pore size of 10-16 meshes are fixed inside, and it is fixed on the frame of the net cage with ropes. When feeding on the 1st day, the depth is 1.8-2 m, and it is raised by 0.1-0.2 m every day thereafter. On the 10th day, it is 0.3-0.5 m below the water surface.

7. The domestication method for improving the conversion rate of floating feed for juvenile fish according to claim 1, characterized in that, during the domestication process of the sinking frame, the mass ratio of the frozen cladocera and the powdery feed is (7-3):(3-7), and the protein content of the powdery feed is above 50%.

8. The domestication method for improving the conversion rate of floating feed for juvenile fish according to claim 1, characterized in that, the domestication of the floating feed is to sprinkle the feed into a square frame made of PVC pipes with a size of 2 m×2 m, and the frame is fixed on the net cage or the wooden stake at the feeding point with ropes; the protein content of the expanded feed and the slow-sinking expanded feed is above 48%.

9. The domestication method for improving the conversion rate of floating feed for juvenile fish according to claim 1, characterized in that, during the domestication process of juvenile fish, 1 g of Schizochytrium powder is added to every catty of all feeds until the domestication is completed.