A closed-loop, factory-scale, end-to-end cultivation method for feed-fed mandarin fish fry based on in-situ purification of bioflocs

Abstract

This invention belongs to the field of aquaculture technology, specifically relating to a closed-loop, factory-style, end-to-end cultivation method for mandarin fish fry based on in-situ purification using bioflocs. This method sequentially completes in-situ biofloc cultivation, closed-loop in-situ prey fish cultivation, in-situ juvenile rearing of mandarin fish, gradient feed acclimatization, and pathogen isolation and monitoring within a closed cultivation tank. Stable bioflocs are formed by inoculating a compound microbial agent containing Bacillus, lactic acid bacteria, and photosynthetic bacteria, and adjusting the carbon-nitrogen ratio, achieving in-situ water purification and biological antibacterial effects. The entire process involves no transfer to other tanks and no introduction of exogenous live prey fish. A three-stage gradient feeding scheme is used to complete feed acclimatization, combined with biofloc-based feeding stimulation and nutritional supplementation, shortening the acclimatization period and improving fry survival rates. This invention effectively isolates exogenous pathogens, reduces stress on mandarin fish fry, and reduces water and antibiotic use, achieving a fully closed-loop, green, and highly efficient factory-style cultivation of mandarin fish fry from start to completion of feed acclimatization.

Description

Technical Field

[0001] This invention belongs to the field of aquaculture technology, specifically relating to a closed-loop, factory-style, full-process cultivation method for feed mandarin fish fry based on in-situ purification of bioflocs. Background Technology

[0002] Currently, the cultivation of feed-fed mandarin fish fry mostly adopts open ponds or semi-open factory farming models, which have prominent problems such as fragmented processes, uncontrollable safety of feed fish, and easy invasion of pathogens. Although biofloc technology has been applied to water purification, existing technologies have not integrated it with closed cultivation systems, focusing only on the water quality control function of a single stage.

[0003] Publicly available patents, such as CN202411251802.X (a mandarin fish feed and a method for artificially acclimating mandarin fish), use open-type aquaculture ponds without pathogen isolation facilities, making it easy for external water and air to introduce pathogens. CN202311644941.4 (a method for acclimating mandarin fish to feed in a factory-scale recirculating aquaculture system) is only used for the acclimation stage of feed mandarin fish, with the acclimation and rearing stages carried out independently. The process of transferring the fish to another pond and transporting them can easily increase stress on the fish. In addition, during the acclimation process, it is necessary to transport the corresponding size of feed fish raised off-site to the mandarin fish fry rearing pond. During the transportation process, the feed fish can easily carry pathogens, resulting in a morbidity rate of over 25% for the mandarin fish fry.

[0004] The core defects and causes of existing technologies are as follows: 1. Non-closed breeding model: The breeding pond is not effectively isolated from the external environment. Water, air, mosquitoes and other factors can all become carriers of pathogens, and it is impossible to prevent the invasion of external pathogens. 2. Fragmentation of the rearing process: The rearing of baitfish and the growth and feeding of mandarin fish fry are carried out in separate ponds. The process of transferring ponds and transportation not only causes stress damage to the mandarin fish fry, but also increases the risk of cross-infection. 3. Limited Function of Bioflocs: Current technologies only utilize bioflocs to degrade pollutants in water bodies, without exploring their potential as a feed source for raising forage fish.

[0005] In summary, existing feed-based mandarin fish fry breeding technologies still lack a highly efficient, factory-scale breeding method that can achieve fully enclosed, in-situ integrated, multi-functional utilization of bioflocs, and low pathogen risk, making it difficult to meet the industry's demand for high survival rates, green and safe, and large-scale fry production. Summary of the Invention

[0006] To address the shortcomings of existing technologies, such as non-closed cultivation models, fragmented processes, single-function bioflocs, and high risk of pathogen domestication, the purpose of this invention is: (1) A closed-loop, factory-style, in-situ culture method is provided, which enables the cultivation of bait fish, the fry rearing of mandarin fish, and the domestication of feed to be completed in the same closed pond, thus isolating the invasion of external pathogens; (2) Construct a dual pathogen control system of "biofloc purification + closed isolation" to eliminate the need for antibiotic use and achieve green cultivation; (3) Reduce stress on mandarin fish fry during transfer to ponds, and improve survival rate and uniformity of size; (4) Optimize the gradient domestication process, shorten the domestication cycle, and reduce breeding costs.

[0007] This invention is achieved through the following technical solution: A closed-loop, factory-scale, end-to-end cultivation method for feed-fed mandarin fish fry based on in-situ purification using bioflocs includes the following steps: (1) In situ culture of bioflocs: Inoculate the closed culture pond with compound microbial agent, use brown sugar and fish feed washed through a 60-mesh sieve as nutrition source, adjust the carbon-nitrogen ratio (C / N) of the water to (15~18):1, and continuously and evenly aerate for 5~7 days to form bioflocs with a particle size of 0.2~0.6 mm and a particle concentration of 5~8 mL / L. (2) Closed-system in-situ culture of prey fish: Fertilized gracilis eggs disinfected with 5 mg / L povidone-iodine for 10 min were used at a rate of 450,000 eggs / m³. 3 The fish were introduced into a closed rearing tank at a high density. During incubation, the C / N ratio was maintained at (15~18):1. After 10~12 days of incubation, when the prey fish reached a length of 0.8~1.0 cm, the density was adjusted to 180,000 fish / m³. 3 ; (3) Enclosed in-situ culturing of juvenile mandarin fish: Mandarin fish fry with a body length of 1.0-1.2 cm, disinfected with 3% saline solution for 5 minutes, were released into the same closed rearing pond at a ratio of 12:1 of prey fish to mandarin fish and were bred to feed acclimatization size. (4) Closed-loop gradient feed acclimatization: The acclimatization was carried out according to a three-stage gradient feeding program, and the entire process was completed in the same closed pool. (5) Pathogen isolation and monitoring: Regularly use PCR to detect pathogens such as Saprolegnia and Flavobacterium columnare to ensure that the pathogens are below the detection limit and that the proportion of beneficial bacteria in the biofloc is ≥ 90%.

[0008] Furthermore, the compound microbial agent mentioned in step (1) is composed of Bacillus, Lactobacillus, and photosynthetic bacteria in a ratio of 3:2:1, with an inoculation concentration of 2×10⁻⁶. 8 CFU / L.

[0009] Furthermore, the mass ratio of brown sugar to feed mentioned in step (1) is 5:1.

[0010] Furthermore, in step (3), when the ammonia nitrogen level is >0.4 mg / L during the crude feed stage, brown sugar is added to adjust the C / N ratio to 20:1, maintaining the biofloc concentration at 10~15 mL / L. The feed fish cultivated using biofloc are added regularly until the mandarin fish fry reach the feed acclimatization standard.

[0011] Furthermore, during the initial stage of step (3), excess bioflocs are collected through a sedimentation tank and discharged into the supporting bait fish breeding pond as a supplement to the feed, thus achieving recycling.

[0012] Furthermore, the three-stage gradient feeding scheme described in step (4) for acclimatization specifically involves: Days 1-3: Feed bait fish that have been cultured using bioflocs; Days 4-6: Gradually mix live bait fish with chilled fish paste that has been UV disinfected for 15 minutes in a ratio of 7:3, 5:5, and 3:7. Add 3% bio-floc dry powder to the fish paste. Days 7-15: Gradually mix fresh fish paste with mandarin fish fry feed with a particle size of 2.0-2.5 mm in a ratio of 7:3, 5:5, and 3:7. Spray the surface of the feed with bio-floc homogenate. Reduce the proportion of fresh fish paste by 10% each day until the feed is completely fed with the feed. After complete feeding, maintain the bio-floc concentration at 8-12 mL / L.

[0013] Furthermore, the enclosed breeding pond is a fully isolated facility, with no transfer to another pond or introduction of live bait fish from outside the breeding area during the breeding process. The incoming and outgoing water and air are disinfected and filtered, and the water exchange rate is 2-5% / day.

[0014] The present invention has the following advantages over the prior art: The technical effects of this invention are achieved through the dual protection of "closed isolation + biofloc purification" and in-situ cultivation throughout the entire process, as detailed below: (1) In-situ throughout the entire process to isolate pathogens: All cultivation steps are completed in the same closed pool without transferring to another pool or transporting. Combined with air filtration and inlet / outlet water disinfection, the invasion of external pathogens is completely isolated. The beneficial bacteria in the biofloc inhibit the growth of endogenous pathogens, and there is no pathogen detection rate throughout the entire cultivation process. (2) In-situ purification, green and environmentally friendly: bioflocs degrade uneaten feed and feces, purify water quality in situ, reduce water consumption, and reduce water exchange rate to 2-5% / day; no antibiotics are needed, and the cultivated mandarin fish fry have no drug residues and meet the standards for pollution-free aquatic products; (3) Reduce stress and improve uniformity: In-situ cultivation throughout the process avoids stress response in mandarin fish seedlings, and the uniformity of size reaches more than 90%, which is 25% higher than that of traditional methods; (4) Efficient domestication and shortened cycle: The gradient domestication process combined with biofloc feeding reduces the domestication cycle to 15 days, which is 40% shorter than the traditional method. Detailed Implementation

[0015] To further explain the present invention, the following specific embodiments are described.

[0016] Example 1: The technical solution of this invention takes in-situ water purification by bioflocs as its core, combined with forage fish cultivation, in-situ acclimation and graded feed training of mandarin fish juveniles, pathogen isolation and monitoring, etc., to achieve no pathogen invasion and no pond transfer operation throughout the entire process, as detailed below: (a) In situ culture of bioflocs 1. Inoculation with compound microbial agent: Inoculate the closed cultivation tank with a compound microbial agent (after acclimation and activation with the original tank water, it is directly sprinkled). This agent is composed of Bacillus, lactic acid bacteria, and photosynthetic bacteria in a ratio of 3:2:1, and the inoculation concentration is 2×10⁻⁶. 8 CFU / L; the microbial agent has both organic matter degradation and antibacterial functions, and can inhibit pathogenic microorganisms such as Saprolegnia and Flavobacterium columnare; Bacillus: "King of Probiotics", Guangzhou Xinhailisheng Biotechnology Co., Ltd.; Lactic acid bacteria: "Lijunduo", Guangzhou Liyang Aquatic Technology Co., Ltd.; Photosynthetic bacteria: "Lishengduo", Guangzhou Liyang Aquatic Technology Co., Ltd.

[0017] 2. Carbon-to-nitrogen ratio control: Add brown sugar as a carbon source, and at the same time, supplement with fish fry feed washed through a 60-mesh sieve (carbon source: feed ratio of 5:1) to adjust the carbon-to-nitrogen ratio (C / N) of the water to (15~18):1. Aerate continuously for 5~7 days until bioflocs with a particle size of 0.2~0.6 mm are formed in the water and the floc concentration is stable at 5~8 mL / L, thus completing the construction. The beneficial bacteria in the flocs can inhibit the reproduction of pathogens through nutrient competition, thereby achieving biological disease control.

[0018] (II) Closed-system in-situ cultivation of bait fish 1. Disinfection and placement of fertilized eggs: Select fertilized eggs from mud carp, disinfect them with a 5 mg / L povidone-iodine solution for 10 min, rinse with clean water, and then place them in a closed culture tank at a density of 450,000 eggs / m². 3 No live bait fish are introduced throughout the entire process to prevent the introduction of pathogens at the source. 2. Biofloc co-cultivation: During the incubation period of prey fish, in addition to feed, brown sugar is supplemented daily to maintain the C / N ratio (15~18):1. The microorganisms of biofloc degrade the residual eggs and feces produced during incubation, and at the same time, the protein and amino acids it is rich in can be used as supplements for the first feed of prey fish. 3. Density control: 10-12 days after hatching, when the prey fish reach a length of 0.8-1.0 cm, weak fry are removed using a siphon method to control the density to 180,000 fish / m². 3 This meets the feeding needs of mandarin fish fry.

[0019] (III) Enclosed in-situ breeding of juvenile mandarin fish 1. Disinfection and release of mandarin fish fry: Select uniformly sized mandarin fish fry (1.0~1.2 cm in length), disinfect them with 3% saline solution for 5 minutes, and release them into a closed rearing pond at a ratio of 12:1 for bait fish to mandarin fish fry. The entire release process is completed in the pond without any transfer to another pond. 2. Biofloc Maintenance and Disease Control: During the coagulation period, monitor the concentrations of ammonia nitrogen and nitrite in the water daily. When ammonia nitrogen > 0.4 mg / L, supplement with brown sugar to adjust the C / N ratio to 20:1 to enhance the purification capacity of the biofloc. Remove excess flocs through sedimentation in a settling tank to maintain the biofloc concentration at 10-15 mL / L. The dominant population of beneficial bacteria inhibits the growth of pathogens, and no additional chemicals are required throughout the process. 3. Relay rearing of baitfish: Excess flocs removed during the growth period of mandarin fish fry are discharged into the baitfish rearing pond to supplement the baitfish feed.

[0020] 4. Growth monitoring: Every 3 to 5 days, sample and measure the body length and weight of mandarin fish seedlings in a closed environment, and screen individuals with differences to ensure uniformity in size.

[0021] (iv) Closed-loop gradient feed acclimatization 1. Domestication preparation stage (days 1-3): Feed the fish with prey fish cultivated using bioflocs; 2. Live bait to frozen fish transition stage (days 4-6): Gradually mix live bait fish and frozen fish paste in a ratio of 7:3, 5:5, and 3:7. The frozen fish paste needs to be disinfected with ultraviolet light for 15 minutes before feeding. Add 3% bio-floc dry powder to the fish paste to enhance its palatability and antibacterial effect. 3. Transition phase from chilled to formulated feed (days 7-15): Gradually mix chilled fish paste with formulated feed (particle size 2.0-2.5 mm) at ratios of 7:3, 5:5, and 3:7. Spray the surface of the formulated feed with a bio-floc homogenate solution homogenized at 1000 r / min. Reduce the proportion of chilled fish paste by 10% each day until the feed is entirely formulated. 4. Post-acclimatization management: After fully feeding with formulated feed, maintain the concentration of biofloc at 8-12 mL / L to continue its role in water purification and disease control.

[0022] (v) Pathogen isolation and monitoring We cultivate and test water pathogens daily throughout the process, and use PCR detection to monitor target pathogens such as Saprolegnia and Flavobacterium columnare to ensure that the pathogen content in the water is below the detection limit. We also regularly test the structure of biofloc microbial community to ensure that the proportion of beneficial bacteria is ≥90%.

[0023] (vi) Work Examples A circular, enclosed culture tank with a diameter of 6 m was selected. After disinfection, a compound bacterial agent was inoculated to construct bioflocs. 450,000 disinfected fertilized gudgeon eggs / m³ were then introduced. 3 After 12 days of incubation, 37,500 disinfected mandarin fish fry / m³ were released. 3 From the initial growth stage to when the mandarin fish fry reached a body length of 3-3.5 cm, in-situ feeding acclimatization was initiated. After 15 days of gradual acclimatization, the mandarin fish fry reached a body length of 5.5-6.2 cm, the feeding acclimatization rate was 100%, the survival rate increased to 90%, and the size uniformity reached 92%. No target pathogens were detected throughout the entire cultivation process, the water change rate was only 2-5% / day, and no antibiotics were used throughout the entire process.

[0024] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A closed-loop, factory-scale, end-to-end cultivation method for feed-fed mandarin fish fry based on in-situ purification using bioflocs, characterized in that, Includes the following steps: (1) In situ culture of bioflocs: Inoculate the closed culture pond with compound microbial agent, use brown sugar and fish feed washed through a 60-mesh sieve as nutrition source, adjust the carbon-nitrogen ratio (C / N) of the water to (15~18):1, and continuously and evenly aerate for 5~7 days to form bioflocs with a particle size of 0.2~0.6 mm and a particle concentration of 5~8 mL / L. (2) Closed-system in-situ culture of prey fish: Fertilized gracilis eggs disinfected with 5 mg / L povidone-iodine for 10 min were administered at a rate of 450,000 eggs / m³. 3 The fish were introduced into a closed rearing tank at a high density. During incubation, the C / N ratio was maintained at (15~18):

1. After 10~12 days of incubation, when the prey fish reached a length of 0.8~1.0 cm, the density was adjusted to 180,000 fish / m³. 3 ; (3) Enclosed in-situ culturing of juvenile mandarin fish: Mandarin fish fry with a body length of 1.0-1.2 cm, disinfected with 3% saline solution for 5 minutes, were released into the same closed rearing pond at a ratio of 12:1 of prey fish to mandarin fish and were bred to feed acclimatization size. (4) Closed-loop gradient feed acclimatization: The acclimatization was carried out according to a three-stage gradient feeding program, and the entire process was completed in the same closed breeding tank. (5) Pathogen isolation and monitoring: Regularly use PCR to detect Saprolegnia and Flavobacterium columnare to ensure that pathogens are below the detection limit and that the proportion of beneficial bacteria in bioflocs is ≥ 90%.

2. The closed-loop, factory-style, full-process cultivation method for feed-fed mandarin fish fry based on in-situ purification of bioflocs according to claim 1, characterized in that, The compound microbial agent mentioned in step (1) is composed of Bacillus, Lactobacillus, and photosynthetic bacteria in a ratio of 3:2:1, with an inoculation concentration of 2×10⁻⁶. 8 CFU / L.

3. The closed-loop, factory-style, full-process cultivation method for feed-fed mandarin fish fry based on in-situ purification of bioflocs according to claim 1, characterized in that, The mass ratio of brown sugar to fish feed mentioned in step (1) is 5:

1.

4. The closed-loop, factory-style, full-process cultivation method for feed-fed mandarin fish fry based on in-situ purification of bioflocs according to claim 1, characterized in that, When the ammonia nitrogen level is > 0.4 mg / L during the crude feed stage in step (3), add brown sugar to adjust the C / N ratio to 20:1, maintain the biofloc concentration at 10~15 mL / L, and regularly supplement with bait fish cultivated using biofloc until the mandarin fish fry reach the feed acclimatization standard.

5. The closed-loop, factory-style, full-process cultivation method for feed-fed mandarin fish fry based on in-situ purification of bioflocs according to claim 1, characterized in that, In step (3), during the initial stage of the bidding process, excess bioflocs are collected through a sedimentation tank and discharged into the supporting bait fish breeding pond as a supplement to the feed, thus achieving recycling.

6. The closed-loop, factory-style, full-process cultivation method for feed-fed mandarin fish fry based on in-situ purification of bioflocs according to claim 1, characterized in that, The three-stage gradient feeding scheme described in step (4) for acclimatization specifically involves: Days 1-3: Feed bait fish that have been cultured using bioflocs; Days 4-6: Gradually mix live bait fish with chilled fish paste that has been UV disinfected for 15 minutes in a ratio of 7:3, 5:5, and 3:

7. Add 3% bio-floc dry powder to the fish paste. Days 7-15: Gradually mix fresh fish paste with mandarin fish fry feed with a particle size of 2.0-2.5 mm in a ratio of 7:3, 5:5, and 3:

7. Spray the surface of the feed with bio-floc homogenate. Reduce the proportion of fresh fish paste by 10% each day until the feed is completely fed with the feed. After complete feeding, maintain the bio-floc concentration at 8-12 mL / L.

7. The closed-loop, factory-style, full-process cultivation method for feed-fed mandarin fish fry based on in-situ purification of bioflocs according to claim 1, characterized in that, The enclosed breeding pond is a fully isolated facility. During the breeding process, there is no transfer to another pond or introduction of live bait fish from outside the site. The incoming and outgoing water and air are disinfected and filtered, and the water exchange rate is 2-5% / day.