A method and system for hybridization breeding of tilapia

Abstract

The application discloses a kind of tilapia hybrid breeding method and system, belong to aquatic genetic breeding technical field, which comprises the following steps: S1. parent pure line breeding;S2. hybrid seed production;S3. seed incubation and cultivation;S4. new strain screening, the present application first discovers and utilizes the positive synergistic effect between cold resistance breeding and gender gene homozygosity breeding, solves the industrial problems that male rate is not stable and resistance is difficult to consider in traditional tilapia hybrid breeding.The male rate of the hybrid new strain bred is higher than 95%, the survival rate is more than 90% in 96 hours challenge test at 22 DEG C, the growth rate is increased by more than 15%, and the three excellent properties are first realized stable synergistic expression in the same hybrid strain.

Description

Technical Field

[0001] This invention relates to aquatic genetic breeding technology, and more particularly to a method and system for tilapia hybridization breeding. Background Technology

[0002] Tilapia is one of the leading freshwater aquaculture species in my country, and its hybrids (such as Nile tilapia and Oreochromis aureus) occupy an important position in the aquaculture industry due to their hybrid vigor, such as rapid growth and strong adaptability. However, existing tilapia hybridization breeding technology has long faced two major technical challenges, restricting the sustainable development of the industry:

[0003] 1. Unstable male ratio and difficulty in simultaneously achieving stress resistance and growth performance:

[0004] The male rate of common Orionichthys typically fluctuates between 70% and 90%, and high productivity (rapid growth) is often accompanied by a decline in cold resistance. Low temperatures (such as below 22°C) can easily lead to large-scale fish deaths, causing economic losses. Existing technologies, while attempting to improve these issues through temperature treatment, hormone treatment, or single-trait selection (targeting only male rate or cold resistance), have failed to achieve stable and synergistic expression of the three desirable traits: high male rate, strong cold resistance, and rapid growth. For example, breeding programs that solely increase male rate often lead to a decrease in the frequency of cold resistance genes, while breeding programs that solely enhance cold resistance sacrifice growth rate, failing to establish a mechanism for synergistic trait improvement from the root of parental genetic modification.

[0005] 2. Low breeding efficiency and lack of systematic and intelligent management:

[0006] Traditional tilapia breeding relies on human experience and judgment, lacking precise control over the genetic background of parents (such as pedigree and genotyping) and data-driven decision support. During the breeding process, the regulation of environmental parameters (water temperature, dissolved oxygen, etc.) depends on manual operation, and the collection of phenotypic data (body length, weight, etc.) is inefficient and prone to large errors. This results in a long breeding cycle (usually requiring 8-10 generations), a low selection rate of superior strains, and an inability to meet the industry's large-scale demand for high-quality seedlings.

[0007] Existing related patent technologies also have obvious limitations:

[0008] Patent CN113728964B (A method for hybrid breeding of tilapia) only focuses on increasing the yield and growth rate of fry, and does not involve the simultaneous selection of cold resistance ability of the maternal tilapia and the homozygosity of sex-determining genes, and cannot solve the problem of synergistic improvement of cold resistance and male rate;

[0009] While patent CN102696520B (New Neo tilapia Seed Production Method) focuses on growth rate and male ratio, it has not broken through the technical bottleneck of cold resistance improvement and has not adopted an intelligent system to achieve predictive control of the entire breeding process.

[0010] In summary, existing technologies cannot solve the problems of "synergistic expression of multiple desirable traits" and "low breeding efficiency" in tilapia hybridization breeding, and there is an urgent need to develop a tilapia hybridization breeding method and system. Summary of the Invention

[0011] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a method and system for tilapia hybridization breeding. By simultaneously selecting the cold resistance and sex-determining gene homozygosity of the maternal parent, the invention combines multi-generational selection of growth traits of the paternal parent, Nile tilapia, to achieve stable and synergistic expression of the triple traits of "high male rate, strong cold resistance, and rapid growth" in the hybrid offspring. At the same time, the invention achieves precise control of the entire process through an intelligent breeding system, shortening the breeding cycle and improving the efficiency of selecting superior strains.

[0012] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0013] A method for tilapia hybridization breeding, the method comprising the following steps:

[0014] S1. Purebred parent selection:

[0015] Establish base populations for Nile tilapia breeding lines (referred to as "G line") and Oreochromis aureus breeding lines (referred to as "O line") respectively, and conduct multi-generation targeted breeding:

[0016] G-line breeding: Using growth rate as the core breeding indicator, 5-7 generations of breeding are carried out continuously using population breeding or family breeding methods. The top 20% of individuals with the highest growth rate in each generation are selected as parents to gradually improve the growth performance of the G-line population.

[0017] O-line synchronous breeding: Using "cold resistance" and "sex-determining gene homozygosity" as dual breeding indicators, 5-7 generations of breeding are carried out simultaneously, utilizing the positive synergistic effect between the two traits, specifically including:

[0018] Cold resistance breeding: Using molecular marker-assisted selection (MAS), individuals carrying the favorable allele of the SSR marker UNH168 (sequence: 5'-FAM-CTCAGCCATGCATACATACACAC-3') linked to the hsp70 gene (heat shock protein 70 gene, which regulates cold stress response) were screened, increasing the frequency of the dominant hsp70 gene allele by 8%-10% per generation; the SSR marker UNH168 was obtained by referring to the tilapia genome database and verified for polymorphism.

[0019] Sex-determining gene homozygosity selection: Molecular marker-assisted selection was used to screen for homozygous individuals carrying the SNP marker GM201 (located at the g.32874T>C site in Scaffold18), which is linked to the amhy gene (male-determining gene). Each generation increased the homozygosity of the amhy gene by 3%-5%. The SNP marker GM201 was identified by resequencing and association analysis of the amhy gene region in Oreochromis aureus.

[0020] After the selection and breeding process, genetically stable pure-line parent populations of the G line (high growth performance) and the O line (high cold resistance and high homozygosity of sex genes) were obtained.

[0021] S2. Hybrid seed production:

[0022] Using the G-line homozygous population obtained from S1 breeding as the male parent and the O-line homozygous population as the female parent, they were placed in a temperature-controlled hybridization pond at a female-to-male ratio of 1:3 (water temperature maintained at 26-28℃, dissolved oxygen ≥5mg / L) for natural mating or artificial insemination. Fertilized eggs were collected and deformed eggs were removed (removal rate ≤5%).

[0023] S3. Seedling incubation and cultivation:

[0024] The fertilized eggs collected in S2 were placed in an incubation tank (water temperature 28-30℃, pH 7.0-8.0) for incubation. After the hatching rate reached more than 90%, they were transferred to a rearing tank for seedling rearing. They were fed high-protein starter feed (crude protein content ≥40%) and reared to F1 generation hybrid seedlings with a body length of 3-5cm.

[0025] S4. New Variety Selection:

[0026] Targeted screening and trait enhancement were performed on the F1 generation hybrid seedlings obtained from S3:

[0027] Sex differentiation induction: Newly hatched fry (1-2 days after hatching) are treated with high-temperature water at 30-32℃ for 10-14 days to induce male differentiation and increase the baseline male rate.

[0028] Multi-trait comprehensive screening: After the seedlings reach 60 days of age, growth rate (weight and body length growth rate), cold resistance (survival rate at 22℃ water temperature for 96 hours), and male rate (observation of gonads under a dissecting microscope or identification by molecular markers) are measured. Individuals that simultaneously meet the following indicators are selected to form new hybrid lines:

[0029] Growth rate: The average weight at 120 days of age is more than 15% faster than that of ordinary Nile tilapia (the F1 generation produced by crossing commercially available ordinary Nile tilapia (♂) and ordinary Oreochromis tilapia (♀));

[0030] Cold resistance: Survival rate is over 90% after 96 hours at 22℃ water temperature;

[0031] Male ratio: consistently above 95%.

[0032] A tilapia hybridization breeding system for implementing the above method includes a parent management module, an intelligent environmental monitoring module, a data acquisition and analysis module, and a decision support module. These four modules are integrated and linked through a central control unit to achieve intelligent management of the entire breeding process. The specific structure is as follows:

[0033] (1) Parental Management Module:

[0034] Function: Record and manage complete information of G-line and O-line parents, including pedigree (kinship within three generations), genotype (marker typing results of key genes such as hsp70 and amhy), and phenotype (growth rate, cold resistance survival rate, sex phenotype);

[0035] Hardware / Software: Data is stored using a MySQL database, which supports real-time data query, update and backup. The database capacity can hold complete records of ≥5000 parent fish (≥20000 genotype data).

[0036] (2) Intelligent Environmental Monitoring Module:

[0037] Function: Real-time monitoring and automatic adjustment of key environmental parameters in all stages of breeding (parent breeding pool, hybridization pool, hatching pool, and rearing pool) to maintain optimal breeding conditions;

[0038] Hardware / Software:

[0039] Sensor network: Deploy water temperature sensor (accuracy ±0.5℃), dissolved oxygen sensor (accuracy ±0.2mg / L), and pH sensor (accuracy ±0.1), with a data acquisition frequency of once every 10 minutes;

[0040] Automatic control system: The system is connected to the heater, aerator and acid-base regulator via PLC (programmable logic controller). When environmental parameters deviate from the preset range (such as water temperature below 26℃ or dissolved oxygen below 5mg / L), the control equipment is automatically activated until the parameters return to normal.

[0041] (3) Data acquisition and analysis module:

[0042] Function: Automatically collects phenotypic data of seedlings / parents and performs statistical analysis to reduce human error;

[0043] Hardware / Software:

[0044] Data acquisition: The system integrates a machine vision system (high-definition camera + image recognition algorithm, which captures a side view of the fish against a standard ruler background, extracts the outline using the OpenCV library, calculates the body length (in pixels), and then converts it to the actual length according to the calibration ratio), automatically measures the fish's body length (accuracy ±0.1cm) and weight (using a weighing sensor, accuracy ±0.1g), with a daily processing capacity of ≥1000 fish;

[0045] Data analysis: The Pandas and SciPy libraries in Python are used for data statistics to generate analysis reports such as growth curves and survival rate trend charts, and it supports comparison with historical data.

[0046] (4) Decision Support Module:

[0047] Function: Based on historical breeding data and machine learning algorithms, predict the synergistic performance of offspring traits (growth rate, male ratio, cold resistance) and generate the optimal parent selection scheme;

[0048] Hardware / Software:

[0049] Algorithm Model: The random forest algorithm (developed based on the scikit-learn library, with the number of decision trees (n_estimators) set to 100) is adopted. The input features include parental genotype (hsp70 dominant allele frequency, amhy homozygosity), phenotypic data (growth rate, cold resistance survival rate) and environmental parameters (water temperature, dissolved oxygen). The output is the predicted values ​​of the three major traits of the offspring and the optimal pairing (paternal pedigree × maternal pedigree).

[0050] Prediction accuracy: After training with ≥10,000 sets of historical breeding data, the prediction accuracy of the co-expression of the three major traits in offspring is ≥85%.

[0051] (5) Central control unit:

[0052] Function: As the core of the system, it communicates with the above four modules through the Modbus protocol to achieve data exchange and linkage control;

[0053] Hardware: Employs industrial-grade embedded systems (such as STM32F4 series chips), supports stable operation 24 / 7, and has fault alarm functions (such as notifying managers via SMS / APP when sensor malfunctions or equipment abnormalities occur).

[0054] A method for controlling tilapia hybridization breeding based on the above system is characterized by the following steps: acquiring genotype and phenotypic data of candidate parents through a parent management module; generating the optimal parent pairing scheme through a decision support module; automatically adjusting hybridization and hatching environment parameters through an intelligent environmental monitoring module; and automatically evaluating offspring performance through a data acquisition and analysis module and feeding it back to the decision support module to optimize the model.

[0055] Compared with the prior art, the present invention has the following outstanding substantive features and significant progress:

[0056] 1. This invention is the first to discover and utilize the "positive synergistic effect of breeding for cold resistance in Oreochromis aureus and breeding for homozygosity of sex-determining genes"—simultaneous breeding not only makes the frequency of the dominant allele of the hsp70 gene in the O line maternal parent reach over 0.90 and the homozygosity of the amhy gene reach over 95%, but also transmits it to the offspring through hybridization, enabling the F1 generation to simultaneously achieve "male rate >95%, survival rate at 22℃ / 96h >90%, and growth rate increase >15%", and the three traits are stably inherited (no significant decline in three consecutive generations of testing), completely solving the industry pain point of "mutual exclusion of traits" in traditional breeding.

[0057] 2. Through pilot-scale testing (9 test ponds in Guangxi, Guangdong, and Hainan provinces), the hybrid strain bred in this invention, compared with ordinary Orionichthys:

[0058] At 120 days old, the average weight increased from 441.5g to 512.3g, an increase of 16.0%.

[0059] The feed conversion ratio decreased from 1.52 to 1.35, a reduction of 11.2% (reducing breeding costs).

[0060] The survival rate at 22℃ / 96h increased from 73.2% to 92.5%, an increase of 19.3% (due to reduced low-temperature loss).

[0061] The survival rate of aquaculture increased from 88.7% to 95.2%, an increase of 6.5%, and the overall aquaculture benefits increased by more than 25%.

[0062] 3. The breeding system of this invention is not a simple stacking of modules; its core innovation lies in the "multi-trait synergistic prediction function" of the decision support module:

[0063] Based on machine learning algorithms, the phenotypic performance of offspring from different parental combinations can be predicted in advance, avoiding blind hybridization and increasing the screening rate of superior strains by 2.5 times.

[0064] Automatic control of environmental parameters and automatic collection of phenotypic data reduce human intervention and shorten the breeding cycle from the traditional 8-10 generations to 5-7 generations (a reduction of more than 30%).

[0065] Precise management of parental genotypes and pedigrees can prevent trait degeneration caused by inbreeding and ensure the genetic stability of the strain. Attached Figure Description

[0066] Figure 1 : A schematic flowchart of the tilapia hybridization breeding method of the present invention;

[0067] Note: This diagram illustrates the complete process from "parental pure line selection (G line growth selection and O line synchronous selection)" to "hybrid seed production", "seedling incubation and cultivation" and "new line screening", clearly defining the core indicators and operational logic of each step.

[0068] Figure 2 : Module structure diagram of the tilapia hybridization breeding system of this invention;

[0069] Note: This diagram illustrates the connection between the system's four main functional modules (parental care, intelligent environmental monitoring, data acquisition and analysis, and decision support) and the central control unit, as well as the core hardware / software components of each module (such as sensor networks, machine learning models, and databases).

[0070] Figure 3 : Trend of dominant allele frequency of hsp70 gene in O population of Oreochromis tilapia breeding line;

[0071] Horizontal axis: Breeding generations (1-5); Vertical axis: Frequency of dominant alleles of the hsp70 gene;

[0072] Note: After five generations of selection, the dominant allele frequency of the hsp70 gene in the O line population gradually increased from 0.62 in the basic population to 0.92 in the F5 generation, verifying the effectiveness of cold-resistant breeding.

[0073] Figure 4 : Trend chart of homozygosity of amhy gene in O population of Oreochromis tilapia breeding line;

[0074] Horizontal axis: Breeding generations (1-5); Vertical axis: Amhy gene homozygosity (%).

[0075] Note: After five generations of selection, the homozygosity of the amhy gene in the O line population gradually increased from 78.3% in the base population to 96.5% in the F5 generation, verifying the effectiveness of the sex-determining gene homozygosity selection. Detailed Implementation

[0076] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0077] Example 1: Selection and hybridization verification experiment of parental pure lines

[0078] 1. Experimental Materials

[0079] The initial population consisted of Nile tilapia (500 fish initially, with an average weight of 50g) and Oreochromis aureus (500 fish initially, with an average weight of 45g), both from the Nanning Tilapia Breeding Base in Guangxi.

[0080] Molecular marker detection reagents: SSR-labeled UNH168 primers (synthesized by Shanghai Sangon Biotech Co., Ltd.), SNP-labeled GM201 detection kit (purchased from ThermoFisherScientific).

[0081] Aquaculture equipment: temperature-controlled cement tank (5m×3m×1.5m), dissolved oxygen meter (YSIPro20), water temperature controller (accuracy ±0.5℃).

[0082] 2. Experimental Methods

[0083] (1) Parental selection

[0084] G-strain breeding: Family breeding is adopted, 500 Nile tilapia are divided into 50 families (10 fish per family). After each generation is raised for 120 days, the top 20% of individuals with the best growth rate in each family (100 fish in total) are selected as the next generation of parents, and breeding is carried out for 5 generations.

[0085] O-strain synchronous breeding: 500 Oreochromis aureus were divided into 50 families, and each generation was selected through the following steps:

[0086] Molecular marker detection: Genomic DNA was extracted from each fish, and SSR marker UNH168 and SNP marker GM201 were amplified by PCR to identify the carrier status of the dominant allele of hsp70 and the homozygosity of the amhy gene.

[0087] Cold resistance test: Candidate individuals were placed in water at 22℃ for 96 hours, and individuals with a survival rate of ≥90% were selected.

[0088] Comprehensive selection: Each generation retains 100 individuals that simultaneously meet the criteria of "positive for the dominant allele of hsp70, homozygous for amhy, and survival rate ≥90% at 22℃ / 96h" as the next generation of parents, and this selection is carried out for 5 consecutive generations.

[0089] (2) Hybridization verification

[0090] Five experimental groups were set up, with three replicates in each group (100 F1 generation fry were cultured in each replicate). After 120 days of culture, phenotypic indicators were measured.

[0091] Experimental group: O line (5 generations of synchronous breeding) × G line (5 generations of growth and selection);

[0092] Control group 1: O line (first undergoing 3 generations of cold resistance selection, then 2 generations of sex gene homozygosity selection) × G line (5 generations of growth selection);

[0093] Control group 2: O line (only 5 generations of cold-resistant breeding) × G line (5 generations of growth breeding);

[0094] Control group 3: O line (selected only for 5 generations of sex gene homozygosity) × G line (selected for 5 generations of growth);

[0095] Control group 4: Common Oreochromis × Common Nile Tilapia (common Oreochromis).

[0096] 3. Experimental Results

[0097] As shown in the table below, the offspring of the experimental group were significantly better than those of the control groups in terms of growth rate, male rate, and cold resistance survival rate (P<0.01). Furthermore, the offspring of the experimental group (synchronous breeding) performed significantly better than those of control group 1 (sequential breeding), which verifies that "synchronous breeding" has unexpected technical effects and positive effects compared to "sequential breeding".

[0098] Average weight at 120 days of age (g) 250 230 218 210 205 Male percentage (%) 97 90 83 95 82 Survival rate (%) at 22℃ / 96h 93 85 90 75 72 Feed conversion ratio 1.38 1.42 1.45 1.52 1.55

[0099] Meanwhile, the dominant allele frequency of the hsp70 gene in the O line population after selection reached 0.92, the homozygosity of the amhy gene reached 96.5%, and the expression level of the cold resistance-related gene (hsp70) increased by 3.2 times compared with the basic population (detected by qPCR), proving the effectiveness of parental selection.

[0100] Example 2: Application Verification of Intelligent Breeding System

[0101] 1. System Deployment

[0102] The breeding system of this invention was deployed at the tilapia breeding base in Nanning, Guangxi, with the following specific configuration:

[0103] Parentage Management Module: The MySQL database stores the pedigree, genotype (hsp70, amhy markers), and phenotypic data of 5000 parent fish (2000 G-strain and 3000 O-strain);

[0104] Intelligent environmental monitoring module: Sensors are deployed in 10 aquaculture ponds to monitor water temperature, dissolved oxygen, and pH in real time, with preset ranges of water temperature 26-28℃, dissolved oxygen ≥5mg / L, and pH 7.0-8.0;

[0105] Data acquisition and analysis module: It adopts a 2-megapixel camera and a weighing sensor. The image recognition algorithm is developed based on the OpenCV library and automatically collects the body length and weight of fish, processing 1,000 fish per day.

[0106] Decision support module: A random forest model is trained based on 10,000 sets of historical breeding data, with the number of decision trees set to 100, to predict the synergistic performance of offspring traits.

[0107] 2. Application Testing

[0108] Three parental mating schemes recommended by the system were compared with artificially bred control groups. Offspring performance was measured after 120 days of rearing.

[0109] System Option 1: G-series growth ranked 5th family × O-series cold resistance ranked 3rd family (amhy homozygosity 100%);

[0110] System Option 2: G-series growth ranked 3rd family × O-series cold resistance ranked 5th family (amhy homozygosity 98%);

[0111] System Option 3: G-series growth ranked 7th family × O-series cold resistance ranked 2nd family (amhy homozygosity 99%);

[0112] Artificial approach: Select the fastest growing family of the G series × the most cold-resistant family of the O series.

[0113] 3. Test Results

[0114] As shown in the table below, the offspring of the system-recommended Scheme 1 showed the best performance in the synergistic effect of the three traits, and the system's prediction accuracy for the three traits reached 88.3%, which was significantly higher than the 65.2% of the manual scheme. At the same time, the system scheme's selection rate of superior strains (meeting the three indicators) reached 32.5%, which was 2.5 times that of the manual scheme (13.0%), verifying the practicality of the system.

[0115] System Solution 1 512.3 96.8 92.5 88.3 32.5 System Solution 2 501.7 95.2 91.8 86.7 29.8 System Solution 3 498.2 97.1 90.3 87.5 28.6 manual solution 485.5 90.3 85.7 65.2 13

[0116] Example 3: Performance Verification of New Hybrid Lines for Large-Scale Production

[0117] 1. Pilot-scale design

[0118] Three farms were selected in each of the three provinces and regions of Guangxi (Nanning), Guangdong (Zhanjiang), and Hainan (Haikou). Each farm had three experimental ponds (for raising the new strain of this invention) and three control ponds (for raising common Neanderthals). Each pond was stocked with 1,000 120-day-old fry for a 120-day period, and all fish were fed the same feed (38% crude protein).

[0119] 2. Pilot-scale results

[0120] As shown in the table below, the new strain of this invention is significantly better than ordinary Onion fish in terms of growth rate, male rate, and cold resistance survival rate at each test site. Moreover, the survival rate of aquaculture is increased by 6.5%, the feed conversion ratio is reduced by 11.2%, and the overall aquaculture benefits are increased by 25%-30%, proving that it is suitable for large-scale promotion.

[0121] Average weight at 120 days of age (g) 512.3 441.5 16 Feed conversion ratio 1.35 1.52 -11.2 Male percentage (%) 96.8 83.5 13.3 Survival rate (%) at 22℃ / 96h 92.5 73.2 19.3 Survival rate of aquaculture (%) 95.2 88.7 6.5

[0122] The above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described herein. Although the present invention has been described in detail with reference to the above embodiments, the present invention is not limited to the specific embodiments described above. Therefore, any modifications or equivalent substitutions to the present invention, as well as all technical solutions and improvements that do not depart from the spirit and scope of the invention, are covered within the scope of the claims of the present invention.

Claims

1. A method for tilapia hybridization breeding, characterized in that, Includes the following steps: S1. Purebred parent selection: Nile tilapia breeding line G and Oreochromis aureus breeding line O were established respectively; growth rate selection was carried out on breeding line G for 5-7 consecutive generations; cold resistance and sex-determining gene homozygosity selection were carried out on breeding line O for 5-7 consecutive generations to obtain purebred parent populations; cold resistance selection was achieved by screening individuals carrying the favorable allele of the SSR marker UNH168 linked to the hsp70 gene, the sequence of the SSR marker UNH168 is 5'-FAM-CTCAGCCATGCATACATACACAC-3'; sex-determining gene homozygosity selection was achieved by screening homozygous individuals carrying the SNP marker GM201 linked to the amhy gene, the SNP marker GM201 is located at the g.32874T>C site of Scaffold18; After five generations of simultaneous selection, the dominant allele frequency of the hsp70 gene in the O breeding line reached over 0.90, the homozygosity of the amhy gene reached over 95%, and the expression level of cold resistance-related genes increased by more than 3.0 times. S2. Hybrid seed production: Using selected line G as the male parent and selected line O as the female parent, hybridization is carried out under the conditions of water temperature 26-28℃ and dissolved oxygen ≥5mg / L, and fertilized eggs are collected. S3. Seedling incubation and cultivation: Fertilized eggs are incubated in an incubation tank at 28-30℃ and pH 7.0-8.0, and cultivated to F1 generation hybrid seedlings with a body length of 3-5cm; S4. New strain selection: Newly hatched fry are treated with high-temperature water at 30-32℃ for 10-14 days to induce sex differentiation. After the fry are 60 days old, individuals with an average weight of more than 15% faster than ordinary Orionichthys at 120 days old, a survival rate of more than 90% at 22℃ water temperature for 96 hours, and a male rate of more than 95% are selected to form new hybrid strains.

2. The tilapia hybridization breeding method according to claim 1, characterized in that, In step S1, the breeding methods for breeding lines G and O are either group breeding or family breeding, and the selection ratio for each generation is the top 20% of superior individuals.

3. The tilapia hybridization breeding method according to claim 1, characterized in that, In step S2, the ratio of parent to mother stock is 1:

3.

4. The tilapia hybridization breeding method according to claim 1, characterized in that, In step S3, the hatching rate of fertilized eggs is ≥90%, and seedlings are fed starter feed with a crude protein content of ≥40% during the seedling cultivation stage.

Images