CN113812354A

CN113812354A - Method for hybridization breeding of snakeheads and snakeheads

Info

Publication number: CN113812354A
Application number: CN202110607841.9A
Authority: CN
Inventors: 王煜恒; 陈军; 周广帅; 王煜轩; 王子怡; 颜子豪; 张子琳; 王会聪; 张坤
Original assignee: Jiangsu Polytechnic College of Agriculture and Forestry
Current assignee: Jiangsu Polytechnic College of Agriculture and Forestry
Priority date: 2021-06-01
Filing date: 2021-06-01
Publication date: 2021-12-21

Abstract

The invention discloses a method for crossbreeding snakehead and snakehead, which comprises the following steps: in autumn before breeding, the Channa argus and the Channa argus are selected as parents for hybridization breeding to be cultivated; reinforced cultivation: transferring the parents of the snakeheads and the snakeheads to a greenhouse for intensive cultivation in the second year; parent selection: selecting the lunar snakeheads and the snakeheads with mature gonads as parents; artificial hastening parturition: carrying out artificial induced spawning on the selected snakeheads and the selected snakeheads; artificial insemination: adopting dry fertilization; hatching management: hatching the fertilized eggs, and hatching the fertilized fries to form membranes; fry rearing: and (5) incubating the fry after the film is hatched until the fry grows to about 1-2cm, and transferring the fry into a pond for culturing. According to the method, the snakeheads and the snakeheads are subjected to distant hybridization by a hybridization breeding technology, and the gene recombination is utilized to obtain a new variety which has the tender meat quality of the snakeheads and the excellent growth characteristics of the snakeheads, so that the new variety is high in growth speed, strong in disease resistance, strong in adaptability and tender in meat quality, and the breeding economic benefit is improved.

Description

Method for hybridization breeding of snakeheads and snakeheads

Technical Field

The invention belongs to the field of cultivation, and particularly relates to a method for crossbreeding snakeheads and monthly snakeheads.

Background

Cross breeding is the most classical breeding method. The hybridization can select the filial generation individuals with the parent excellent character through the separation and recombination of parent genes. Hybridization can be divided into related hybridization and distant hybridization according to the relationship between parents and parents. Distant hybridization refers to hybridization between species, genus, and subfamily, and even between types of organisms with more distant relationships. It can recombine the genomes of male parent and female parent, change the phenotype and genotype of filial generation, break through intraspecies limitation and expand genetic variation to generate new variation type or new species. In fishery, the utilization of heterosis has become an important way to improve fishery yield.

Channa argus belonging to Perciformes, Pandales (Ananatadei), snakehead (Channidae), snakehead (Channa), except plateau, mainly distributed in the Yangtze river basin and the north to the Heilongjiang river, and also distributed in the south of the Yangtze river, but less frequently. The snakehead fish has the characteristics of large individual, fast growth and low temperature resistance, the average fry bred in 6 months in the year can grow to 200-300 g, and the fry can grow to 1000-2500 g in the next year.

Channa argus (Channa asiatica) belonging to the order Perciformes, the suborder Pandanoidea (Ananatadei), the family Trichidaceae (Channidae), the genus snakehead (Channa), large, wide, flat, short, blunt, large in mouth, and thick in nasal tube, extending forward over the upper lip. The scale is large, and the scale at the top of the head is enlarged but irregular; the head-side scales are also larger. Dorsal and gluteal fin base length; the pectoral fin and the tail fin are both circular; no ventral fin. The body is black or gray black, and the abdomen is grey white. 2 black longitudinal bands are arranged at the back head side of the eyes, extend to the gill cover, and are bent to the base of the pectoral fin; 7-9 transverse belts with forward pointed ends are arranged on the body side; 1 black eye-shaped spot is arranged on the tail fin substrate, and the spot is of a pearl color or is a bright spot of 1 circle of pearl color; the whole body is full of bead bright spots, and the dorsal fin and the gluteal fin are respectively provided with a plurality of rows of bead bright spots, particularly the male is more remarkable. Mainly distributed in the marshland stream of vast hills and mountain areas in the south of the Yangtze river, and is rarely found in the north of the Yangtze river, and is a wild carnivorous small-sized fierce fish. The snakehead fish meat is tender in meat quality and delicious in taste, has a plurality of pharmacological actions of nourishing yin, enriching blood, removing blood stasis, promoting tissue regeneration and the like, is favored by people over snakehead and snakehead, and is regarded as high-grade health care nutritional food by citizens of China including Shuangguang, Shuanghu, Hongkou and Australia and southeast Asia. However, the growth rate of the channa asiatica is slow, the channa asiatica can reach sexual maturity after being cultured for 1 year, the average weight is 100g-250g, and the maximum weight is close to about 500 g.

In recent years, many breeding works for snakehead fish have been carried out. An artificial breeding method for the hybridization of female channa maculata and male channa maculata is proposed by von dawn (patent number: 201010241841.3); scholars in the hybrid snakehead paper propose a hybrid propagation method by taking snakeheads as female parents and snakeheads as male parents (hybrid snakeheads J, ocean and fishery, 2019(09): 42.); cultivation of all-male hybrid snakehead is carried out by Zhaojian et al (patent number: 201910682816. X). Most of the snakeheads and the channa maculata are utilized to carry out positive and negative mating.

Studies such as Yangchuning and the like show that the number of chromosomes of the water-series snakeheads in the Dongting lake is 2 n-48, the number of chromosomes of the channa maculata is 2 n-42, the number of chromosomes of the channa maculata is 2 n-44, the channa maculata is the most original group in the 3 snakehead fishes, and the channa maculata is the most specialized group; the relationship between the snakeheads and the monthly snakeheads is farthest, and the relationship between the snakeheads and the snakeheads is closer than that between the snakeheads (Yanchung, Liu Liang nationality, Populegon, Hanqing, Zhongwan. Dongting lake water system, the chromosome group type analysis of 3 types of snakeheads [ J ]. the Sichuan university of agriculture academic newspaper, 2016,34(04):493 498.). Based on the research results, the hybridization of the snakeheads and the channa maculata is already applied to production, the snakeheads and the channa maculata belong to the same genus and different species, the currently cultured snakeheads belong to fishes with larger body types of snakehead fishes, the growth speed is high, but the diseases are more in the culture process, and the meat quality is not tender enough compared with the snakeheads; the Channa argus has tender meat and delicious taste, but has small body size, slow growth speed and high requirement on environment, and the current large-scale culture area is small. Reports about crossbreeding of the snakeheads and the snakeheads are not seen.

Disclosure of Invention

The purpose of the invention is as follows: aiming at the problems in the prior art, the invention provides a method for hybridization breeding of snakeheads and monthly snakeheads.

The technical scheme is as follows: in order to realize the aim, the method for crossbreeding the snakeheads and the snakeheads comprises the following steps:

(1) parent breeding: in autumn of the previous year of breeding, the Channa argus and the Channa argus are selected as parents for hybridization breeding, breeding is carried out in a stocking pond, and after the water temperature is reduced in 11-12 months, the breeding fishes are transferred to a greenhouse for breeding;

(2) reinforced cultivation: gradually raising the temperature in 3-4 months in the second year, and carrying out intensive culture on the snakeheads and the snakeheads;

(3) parent selection: selecting mature gonad of Channa argus and Channa argus as parent in 5-6 months

(4) Artificial hastening parturition: carrying out artificial induced spawning on the snakeheads and the snakeheads selected in the step (3) by adopting a luteinizing hormone releasing hormone analogue No. 2 and chorionic gonadotropin;

(5) artificial insemination: adopting dry fertilization;

(6) hatching management: hatching the fertilized eggs by adopting micro-flow water, and providing sufficient dissolved oxygen to promote hatching; after fertilization, the fry is hatched to form a film, and the fry can be obtained;

(7) fry rearing: after hatching the membrane, the yolk sacs of the fries disappear, the fries can swim smoothly, the fries begin to be eaten after opening, and the fries can grow to about 1-2cm after being cultivated, and then the fries can be transferred into a pond for cultivation.

Wherein the selected channa argus in the step (1) is more than 1 foot age, has no disease or injury and has a body weight of more than 100g, and the selected channa argus is more than 2 foot ages and has a body weight of more than 600g as a parent for hybridization breeding.

In the step (2), in 3-4 months in the second year, the parents of the snakeheads and the snakeheads are transferred into a greenhouse for intensive cultivation; feeding high protein compound feed combined with fresh fish and shrimp as bait, periodically flushing water to promote gonad maturation, controlling water temperature in the greenhouse by heating facility at 20-25 deg.C during cultivation, and periodically checking parent gonad development condition.

Selecting high-quality parents with gonads developed to the IV stage in the step (3) for hybridization breeding, and selecting male fishes of snakeheads and snakeheads: the genital pore is narrow and is slightly protruded, the tail end is slightly red, and the semen flows out when the two sides of the abdomen are slightly squeezed; selecting female fishes of snakeheads and monthly snakeheads: the abdomen is enlarged and soft, the middle of the abdomen is faced upward, obvious grooves appear, the outline of the ovary is obvious, and the genital orifice is slightly red and swollen and protruded.

Preferably, in the step (3), the female body weight of the channa asiatica is more than 200g, and the male body weight is more than 300 g; the female body weight of the snakehead is more than 750g, and the male body weight is more than 1000 g.

The oxytocin in the step (4) comprises a luteinizing hormone releasing hormone analogue No. 2 (LRH-A2) and chorionic gonadotropin (HCG); the injection dosage of female snakehead fish is as follows: HCG (1000-1200IU/kg) + LRH-A2(10-15 μ g/kg); the male fish dose is HCG (500-600IU/kg) + LRH-A2(5-7.5 μ g/kg); injecting the female fish and the male fish by one needle; the oxytocic drug dosage of the female fish of the snakehead is as follows: HCG (1500-; the male fish dose is HCG (750) -900IU/kg) + LRH-A2(7.5-9 μ g/kg). The two-shot method is adopted, 1/3 in the first injection dose is separated from the two needles by 15-18 h.

Preferably, the oxytocic dose of the female fish and the snakehead is as follows: HCG (1600IU/kg) + LRH-A2(16 μ g/kg), adopting a two-time injection method, 1/3 of the first injection dose, and 15-18h of space between two needles; male snakeheads were injected with one needle, HCG (500IU/kg) + LRH-A2 (5. mu.g/kg), both injected at the base of the pectoral fin.

Wherein, the water temperature is controlled at 25-26 ℃ during the induced spawning period in the step (4), the effect time of the snakeheads is 19-22 hours, the effect time of the snakeheads is 38-42 hours, and the early induced spawning of the snakeheads is carried out.

Further, all injections were given using the base of the pectoral fin; the parents are put back into a cement pool after being injected with hormone, and the male and female fishes of the snakehead and the snakehead are respectively separated for production.

The first pairing method: the female Channa argus is hybridized with the male Channa argus. Wherein, the dry fertilization process adopted in the step (5) is that after the effect period is reached, firstly, the abdomen of the female channa obscura is slightly squeezed, and the ovum is collected into a clean washbasin; rapidly extruding the abdomen of the male snakehead, dripping the semen into a washbasin, continuously stirring by using feathers to uniformly mix the semen and the ovum, adding a sperm activating solution after uniformly mixing, rapidly stirring, removing upper-layer foam, and cleaning for 2-3 times, wherein all the insemination operation is completed within 3 min; if the hybridization dry fertilization method of the male channa lunata and the female channa obscura is adopted, the method is the same as the first pairing mode.

In the conventional snakehead fish breeding process, female and male 1:1 pairing is mostly adopted for natural spawning and insemination, but as the difference between the individuals of the snakeheads and the snakeheads is quite large, fighting and other situations are easy to occur during natural pairing, the fertilized eggs are obtained by adopting an artificial insemination method. After artificial spawning induction, estrus expression is regularly observed, and fertilized eggs obtained by hybridization are golden yellow and oily eggs and float on the water surface.

Wherein, the incubation with micro flowing water in the step (6) is specifically to place the fertilized eggs in an incubation cylinder, incubate with micro flowing water, and simultaneously, the bottom of the incubation cylinder is oxygenated by a microporous nano disc, so as to provide sufficient dissolved oxygen to promote incubation; during the incubation period, the water temperature is controlled at 27-28 ℃. After fertilization for 36-42h, the fry is taken out of the film to obtain the fry; in order to control the occurrence of fish egg saprolegniasis during hatching, the fish egg is soaked in 5-10ppm of thioether-containing floxacin for 10-20 seconds before hatching, and white dead eggs are removed in time when being found in a hatching cylinder during hatching.

And (3) after the fry are hatched and membrane is removed in the step (7), the yolk sac disappears, the fry can swim horizontally, the fry start to be fed in an opening, the fry need to be transferred to a culture pond from an incubation cylinder for first-stage culture of the fry, the fry can grow to 1-2cm after being fed in the opening until the fry is removed from the membrane for 10 days by adopting plankton feeding, the fry can be transferred to a pond for culture, the fry is continuously subjected to two-stage culture, and adult fish culture is performed to obtain two hybrid snakehead fish with excellent growth performance.

First-stage cultivation of seedlings: transfer the initial hatch feeding fry to an indoor cement pond (4 m)X 4m x 1.5m), cleaning and sterilizing the cement pool in advance, and putting 8000-10000 tails/m²The initial bait for the hybrid snakehead fry comprises rotifers, small cladocera and copepods, the bait organisms need to be cultivated in advance, then the bait is fished by a 80-100-mesh plankton net and filtered by a 40-mesh bolting silk, then the fish fries are fed for ingestion, the fish fries are fed for 3 times a day, once in the morning, at noon and evening, the plankton is fed until the fish fries come out of the film for 10 days (the rotifers are fed within 2-3 days before the fish fries are put in, and then the fish fries are converted into the cladocera to be fed), generally after about 10 days of cultivation, the fish fries can grow to about 1-2cm, and then the fish fries can be transferred into a pond for cultivation.

Fry second stage cultivation:

(1) pond preparation before seeding

Selecting a pond with about 3-5 mu, and enclosing 300-400m meshes in the pond²Adding water to 1-1.2m in the area, using 135 plus 150 kg/mu of quicklime to thoroughly carry the pond with water for cleaning, and draining the pond water after 10 days. Then adding clean river water filtered by 3 layers of 80-mesh net, and adding water for 1.2-1.5 m. Then using chlorine dioxide to disinfect the water body, 1 per 667m²100-200g for 1 m water depth. Calcium peroxide (5-10 g/m) is used for the third day after water body disinfection³) Detoxification, using Bacillus (2 g/m) on day four³) + zeolite powder (4 g/m)³) Adjusting water quality, using photosynthetic bacteria (4 ml/m) on day five³) + zeolite powder (4 g/m)³) Adjusting water quality, and spraying 1-2 kg/mu.m of algae cultivation paste for cultivating algae and fertilizing water on the sixth day. Then checking the number of zooplankton in the water body to reach 5-10/ml. And (5) putting the fry.

(2) Fry feeding: 500-800 fish fries/m with the specification of 1-2cm are put in the pond enclosure²。

(3) Feeding management: the fry at this stage also needs to eat cladocera, and can eat compound feed after domestication. The domestication is as follows: sprinkling soybean milk every day after putting fry for culturing twigs (each 667 m)²Soaking water surface with 5-10kg dry semen glycines, grinding into soybean milk), sprinkling once in the morning, at noon and evening, and performing the operation within 10-15d before cultivation.

While culturing the live zooplankton, feeding frozen cladocera (10-20 g per ten thousand per day) 3 times a day for 3 days.

And 4-6 days after seedling placing, mixing the frozen cladocera and the tubificidae, and feeding the mixed tubificidae and tubificidae by 20% on the first day, 50% on the second day and 80% on the third day. 20-30g of the mixture is fed to every ten thousand fries every day, 4 times a day.

And (5) feeding 7-9 days after seedling placing by mixing the tubificidae, the iced fresh minced fillet and the mixed feed No. 0. 70% of tubificidae on the first day, 30% of iced fresh minced fillet, 40% of tubificidae on the second day, 50% of iced fresh minced fillet, 10% of mixed feed 0, 20% of tubificidae on the third day, 60% of iced fresh minced fillet and 20% of mixed feed 0. 30-50g of the mixture is fed to every ten thousand fries every day, 6 times a day.

And (5) gradually switching to feeding of all the compound feed 10-25 days after seedling placing. 10-13d, 60% of ice fresh minced fillet and 40% of mixed feed No. 0; 14-16d, 40% of ice fresh minced fillet + 60% of mixed feed No. 0; 17-19d, 20% of ice fresh minced fillet and 80% of compound feed No. 0; 20-22d of frozen fresh minced fillet + 80% of mixed feed No. 1; after 23d, feed 1 is formulated. 50-300g of mixed material is fed to every ten thousand fries every day, and the feeding amount is gradually increased according to the actual situation.

(4) Screening and expanding a culture area: the cultivation time in the whole stage is about 25d, the fry needs to be screened once every 10d, 3% -5% of fries with large specifications are sorted out and put into other ponds for cultivation.

During the first screening, the area surrounded by the mesh can be expanded to 600-800m². And after the second screening, removing the net sheets, and expanding the fry breeding area to the whole pool.

(5) Water quality regulation and disease prevention and control: during the cultivation period, water quality regulation is carried out by using bacillus and photosynthetic bacteria every 3-5 days according to product specifications. Every 5-7 days, using povidone iodine solution 20-30g/m³And (4) disinfecting the water body to prevent bacterial diseases.

After 2 stages of cultivation, the fry can grow to 5-8 cm.

Fish breeding

(1) Preparation before stocking: the pond size is 5-8 mu, and the operation is the same as two-stage cultivation of the fry.

(2) Fry stocking: to be suspended in the pondAfter a large number of fish fries appear, the fish fries with uniform specifications are thrown. Each 667m²1-2 ten thousand fish fries with the specification of 5-7cm are thrown in the area.

(3) Feeding management: the special compound feed for snakeheads is fed, the feeding amount is 3% -5% of the weight of snakeheads, the feeding period follows the four-fixed and three-fixed principle (four fixed: fixed time, fixed point, fixed quality and fixed quantity; three fixed: weather, water quality and fish condition), and the feeding amount is flexibly adjusted according to the situation.

(4) Water quality and disease prevention and control: two-stage cultivation stage of same fry

After the cultivation in this stage for 3-5 months, the plant can grow to 130 g/tail of 100-. Adult fish culture

(1) Preparation before stocking: the pond size is 10-15 mu, and the specific operation is the same as two-stage cultivation of the fry.

(2) Breeding fish seeds: after a large amount of phytoplankton appears in the pond, fish seeds with uniform specifications are put in. The fingerlings can be soaked in 5% salt solution for 10-15 minutes before being put into the pond. Each 667m²The area is provided with 5000-.

(3) Feeding management: the special compound feed for the snakeheads is fed in the stage, the feeding amount is 3% -5% of the weight of the snakeheads, the feeding period follows the four-fixed-three-watching principle (four fixed-time, fixed-point, fixed-quality and fixed-quantity; three watching weather, water quality and fish condition), and the feeding amount is flexibly adjusted according to the situation.

After the cultivation for more than 5 months at this stage, the standard of marketing can be reached.

The principle is as follows: the offspring obtained by the hybridization of the existing snakeheads and the snakeheads can have the advantages that the snakeheads can eat the compound feed. However, the hybrid snakeheads have the defects that the meat quality is inferior to that of the snakeheads, and after the hybrid snakeheads eat compound feed, the visceral abdominal fat is large and the edible parts are reduced, so that a new variety needs to be bred to solve the problems.

The Channa argus and the Channa argus belong to different species of the same genus, and the hybridization of the Channa argus and the Channa argus is intraspecific interspecies distant hybridization, so that the feasibility is completely realized. The invention firstly provides the hybridization of the Channa argus and the Channa argus, firstly solves the problem that the sexual maturation time of the Channa argus is earlier than that of the Channa argus in the actual cultivation process, and also solves the problem that the Channa argus and the Channa argus are difficult to naturally propagate due to the special individual species in the artificial insemination mode, so that the hybridization breeding of the Channa argus and the Channa argus in the production process becomes possible.

The method solves the problem that the meat quality of the conventional hybrid snakeheads, the snakeheads and the snakehead hybrid snakeheads is not as good as that of the snakeheads through the hybridization method of the snakeheads and the snakeheads, and simultaneously solves the problems that the meat quality of the snakeheads is tender, but small and slow in growth speed. In addition, the hybrid snakehead fish obtained by the invention has less visceral abdominal fat and more edible parts, and is obviously superior to the existing hybrid snakehead fish.

Has the advantages that: compared with the prior art, the invention has the following advantages:

1. firstly, a method for breeding a new variety by hybridizing snakeheads and snakeheads is provided;

2. the fertility rate, the hatchability rate and the emergence rate of the new species of hybrid snakeheads are all higher than those of common snakeheads and common snakeheads;

3. the new hybrid snakehead fish has the advantages of high growth speed, strong adaptability, strong disease resistance, tender meat quality and richer nutrition.

4. The hybridization method has the advantages of short fish culture time, high maturity, low requirements on site and facilities, and simple and easy operation.

Detailed Description

The present invention will be further described with reference to the following specific examples.

The experimental methods described in the examples are all conventional methods unless otherwise specified; the reagents and materials are commercially available, unless otherwise specified.

Among them, Bacillus (Bayer company, trade name: Youcaile); photosynthetic bacteria (favorable aquatic products, product name: much of interest); compound feed No. 0 (guangdong yuehai feeds, raw fish fry No. 0); feed 1 (Guangdong Yuehai feed company, raw fish fry feed 1); the compound feed special for snakeheads (a whole series of raw fish feeds of Guangdong Yuehai feed company are all used).

Example 1

1. Parent breeding

Selecting the Channa argus with the age of more than 1 foot and no disease or injury in the 10 months of the previous year, taking the Channa argus with the weight of more than 100g and the Channa argus with the weight of more than 2 feet as parents for hybridization breeding, breeding in a stocking pond, separately breeding the two kinds of fishes with the density of 600 fish tails per mu, feeding expanded Channa argus feed in the whole process, wherein the daily feeding rate is 5 percent of the weight, feeding for 3 times a day, keeping the water level at 1.5-2m in the breeding process, and regulating the water quality by using bacillus and photosynthetic bacteria every week; in 11 months, the breeding fish are transferred into the greenhouse to be continuously cultivated along with the reduction of the air temperature.

2. Intensive cultivation

In the next 3 months, the snakeheads and the snakeheads are intensively cultivated by adopting a gradual temperature rise mode. Feeding a high-protein compound feed which is combined with fresh fishes and shrimps to serve as bait, mixing the high-protein compound feed (raw fish compound feed of Guangdong Yuehai company) and the fresh fishes and shrimps (stirred into minced fillet) according to the mass ratio of 3:1, and feeding for 3 times a day, wherein the daily feeding rate is 5 percent of the weight. And periodically (2 hours per day, gradually increasing to 4 hours later) flushing water to promote gonad maturation. During the cultivation period, the temperature of water in the greenhouse is controlled by heating facilities to be 20-25 ℃, the parent gonad development condition is regularly checked from the first ten days to the middle ten days of the month 4, the parent gonad development condition is checked once every 2-3 days, and the parent gonad development condition is checked 1 time every day in the last ten days of the month 4.

Wherein the intensified cultivation temperature is gradually increased, the water temperature in the greenhouse is 20 ℃ in 3 months, the temperature needs to be slowly increased, the temperature is increased by 0.5 ℃ for 1 day, then the temperature is maintained for 1-2 days, then the temperature is increased by 0.5 ℃ again, the temperature is maintained for 1-2 days until the temperature is increased to 25 ℃, and then the temperature is maintained for 25 ℃.

3. Selecting parents

Selecting female channa obscura with mature gonads in month 5, wherein the body weight is more than 200g, the abdomen is enlarged and soft, an obvious groove appears in the middle of the abdomen, the outline of the ovary is obvious, and the reproductive hole is slightly red and swollen; male snakeheads with mature gonads have the weight of over 1000g, narrow and small genital pores, slight protrusions and reddish tail ends, and semen flows out from two sides of the abdomen after being slightly squeezed.

4. Artificial hasten parturition

Oxytocin includes luteinizing hormone releasing hormone analog No. 2 (LRH-A2), chorionic gonadotropin (HCG). The oxytocic drug dosage of the female fish and the snakehead is as follows: HCG (1600IU/kg) + LRH-A2(16 μ g/kg), using two injections, 1/3 in the first injection, with 15h separation between the two needles. Male snakeheads were injected with one needle, HCG (500IU/kg) + LRH-A2 (5. mu.g/kg). Both were injected at the base of the pectoral fin.

The water temperature is controlled to be 25-26 ℃ in the induced spawning period, the effect time of the snakeheads is about 21 hours, the effect time of the snakeheads is about 40 hours, and the induced spawning of the snakeheads is started about 19 hours in advance in order to ensure the synchronism of spawning and insemination. All injections were given at the base of the pectoral fin. The parents are put back into a cement pool after being injected with hormone, and the male and female fishes of the snakehead and the snakehead are respectively separated for production.

5. Artificial insemination

And (4) adopting dry fertilization. After the effect period is reached, firstly, slightly pressing the abdomen of the female channa obscura, collecting the eggs in a clean washbasin, and collecting 3-5 eggs of the female channa obscura; then selecting 1 male snakehead, rapidly extruding the belly of the male snakehead, dropping semen into a washbasin, continuously stirring for 10-30 s with feathers to uniformly mix the semen and the ovum, adding a sperm activating solution after the mixing is finished, rapidly stirring for 5-10 s, removing upper-layer foam, cleaning for 2-3 times with clear water until the upper layer has no foam, removing redundant semen, completing artificial insemination, and obtaining golden oily fertilized eggs; all the above insemination procedures were required to be completed within 3 min.

Wherein the activating solution is prepared by mixing sodium chloride, potassium chloride, calcium chloride, sodium bicarbonate, glucose and water, and each liter contains 9.5g of sodium chloride, 0.6g of potassium chloride, 0.25g of calcium chloride, 0.7g of sodium bicarbonate and 12g of glucose.

6. Hatching management

Placing the fertilized eggs in an incubation cylinder, incubating by using micro-flow water, and simultaneously, oxygenating the bottom of the incubation cylinder by using a microporous nano disc to provide sufficient dissolved oxygen to promote incubation; the water temperature was controlled at 28 ℃ during incubation. And (4) after fertilization for 40h, the fry is taken out of the membrane, and the fry can be obtained. In order to control the occurrence of fish egg saprolegniasis during hatching, the fish egg can be soaked by 5-10ppm of thioether fleroxacin for 10 seconds before hatching, and white dead eggs are removed in time when being found in a hatching cylinder during hatching.

7. Fry rearing

3d after hatching and membrane removal, the yolk sac disappears, the fry can swim smoothly, the fry starts to be opened and fed, and the fry needs to be transferred to a culture pond from a hatching jar for first-stage culture of the fry.

First-stage cultivation of seedlings: transferring the fry to a cement pond (4m multiplied by 1.5m) in a culture pond room, cleaning and sterilizing the cement pond in advance, and putting 10000 fish fries/m²The initial bait for the hybrid snakehead fish is rotifer, small cladocera and copepods, the bait organisms need to be cultured in advance, then the zooplankton is fished by a plankton net with 80-100 meshes and filtered by a 40-mesh bolting silk, and then the fish fries are fed for feeding. Feeding rotifers after the film is taken out and the food is eaten, feeding 20g rotifers every ten thousand tails for 5 times a day, and feeding for 3 days without polluting water quality after more rotifers are thrown. Then the rotifers are gradually converted into cladocerans and copepods, 15g of the feed is fed every ten thousand of the rotifers, and the feeding is carried out for 5 times a day. About 10 days after the film is discharged, the film can generally reach about 1-2cm, and then the film can be transferred into a pond for cultivation.

Fry second stage cultivation:

(1) pond preparation before seeding

Selecting a pond with about 3 mu area, and enclosing 400m of net pieces in the pond²In the area (2), water is added to 1.2m, 150 kg/mu of quicklime is used for thoroughly cleaning the pond with water, and the pond water is drained after 10 days. Clean river water filtered through a 3-layer 80 mesh screen was then added, and water was added at 1.5 m. Then using chlorine dioxide to disinfect the water body, 1 per 667m²150g for a water depth of 1 m. Calcium peroxide (5 g/m) is used on the third day after water body disinfection³) Detoxicating by using Bacillus (2g/m3) + Zeolite powder (4 g/m) on the fourth day³) Adjusting water quality, using photosynthetic bacteria (4 ml/m) on day five³) + zeolite powder (4 g/m)³) Adjusting water quality, and watering and sprinkling algae cultivation fertilizing water with algae cultivation paste (1 kg/mu. m) on the sixth day. Then checking the number of zooplankton in the water body to reach 5-10/ml. And (5) putting the fry.

(2) Fry feeding: putting 600 fish tails/m with the specification of 1-2cm in a pond enclosure²。

(3) Feeding management: fry trayThe stage is also feeding cladocera, which needs to be acclimatized to feed a compound feed. Sprinkling soybean milk every day after putting fry for culturing twigs (each 667 m)²Soaking water surface with 5kg dry semen glycines, grinding into soybean milk), sprinkling once in the morning, at noon and evening, and performing the operation within 10-15d before cultivation.

While culturing the live zooplankton, the frozen cladocera (15 g per ten thousand branches per day) needs to be fed for 3 times a day and fed for 3 days continuously.

And 4-6 days after seedling placing, mixing the frozen cladocera and the tubificidae, and feeding the mixed tubificidae and tubificidae by 20% on the first day, 50% on the second day and 80% on the third day. 25g of the mixture is fed to every ten thousand fries every day, 4 times a day.

And (5) feeding 7-9 days after seedling placing by mixing the tubificidae, the iced fresh minced fillet and the mixed feed No. 0. 70% of tubificidae on the first day, 30% of iced fresh minced fillet, 40% of tubificidae on the second day, 50% of iced fresh minced fillet, 10% of mixed feed 0, 20% of tubificidae on the third day, 60% of iced fresh minced fillet and 20% of mixed feed 0. Feeding 40g of the mixed material every ten thousand fries every day, 6 times a day.

And (5) gradually switching to feeding of all the compound feed 10-25 days after seedling placing. 10-13d, 60% of ice fresh minced fillet and 40% of mixed feed No. 0; 14-16d, 40% of ice fresh minced fillet + 60% of mixed feed No. 0; 17-19d, 20% of ice fresh minced fillet and 80% of compound feed No. 0; 19-22d, 20% of ice fresh minced fillet, 40% of mixed feed No. 1 and 40% of mixed feed No. 0; after 23d, feed 1 is formulated. Feeding 200g of mixed materials every ten thousand fries every day, and gradually increasing the feeding amount according to the actual situation.

(4) Screening and expanding a culture area: the cultivation time in the whole stage is about 25d, the fish fries with larger specifications are sorted once every 10d, and the fish fries are put into other ponds for cultivation.

During the first screening, the area enclosed by the meshes can be enlarged to 700m²Left and right. And after the second screening, removing the net sheets, and expanding the fry breeding area to the whole pool.

(5) Water quality regulation and disease prevention and control: during the cultivation period, water quality regulation is carried out by using bacillus and photosynthetic bacteria every 3-5 days according to product specifications.Every 5-7 days, using povidone iodine solution 20-30g/m³And (4) disinfecting the water body to prevent bacterial diseases.

After 2 stages of cultivation, the fry can grow to 5-8 cm.

Fish breeding

(1) Preparation before stocking: the pond size is 6 mu, and the operation is carried out in the same two-stage cultivation of the fry.

(2) Fry stocking: and after a large amount of zooplankton appear in the pond, putting the fish fries with uniform specifications. Each 667m²1 ten thousand fish fries with the specification of 5-8cm are thrown in the area.

(3) Feeding management: the special compound feed for snakeheads is fed, the feeding amount is 3% of the weight of snakeheads, the feeding period follows the four-fixed three-fixed principle (four fixed: fixed time, fixed point, fixed quality and fixed quantity; three fixed: weather, water quality and fish condition), and the feeding amount is flexibly adjusted according to the situation.

(4) Water quality and disease prevention and control: and two-stage cultivation with the fry.

After the cultivation in this stage for 3-5 months, the plant can grow to 130 g/tail of 100-.

Adult fish culture

(1) Preparation before stocking: the pond size is 15 mu, and the specific operation is the two-stage cultivation of the fry.

(2) Breeding fish seeds: after a large amount of phytoplankton appears in the pond, fish seeds with uniform specifications are put in. The fingerlings can be soaked in 5% saline water for 15 minutes before being put into the pond. Each 667m²The area is put with 5000 tails of the fry with the specification of 100-.

(3) Feeding management: the special compound feed for the snakeheads is fed in the stage, the feeding amount is 3% of the weight of the snakeheads, the feeding period follows the four-fixed-three-watching principle (four fixed-time, fixed-point, fixed quality and fixed quantity; three watching-time, weather, water quality and fish condition), and the feeding amount is flexibly adjusted according to the situation.

(4) Water quality and disease prevention and control: and two-stage cultivation with the fry. After the cultivation for more than 5 months at the stage, the market specification can be reached, and the hybrid snakehead with excellent growth performance can be obtained.

Example 2

Example 2 the same procedure as in example 1 was followed, except that:

in the step (3), in 5 months, selecting female snakeheads with mature gonads, wherein the body weight is more than 750g, the abdomen is enlarged and soft, an obvious groove appears in the middle of the abdomen, the outline of the ovary is obvious, and the reproductive hole is slightly red and swollen; the male channa obscura with mature gonads has the weight of more than 300g, narrow and small reproduction holes, slight processes and reddish tail ends, and semen flows out from two sides of the abdomen after being slightly squeezed.

In step (4), the oxytocin includes luteinizing hormone releasing hormone analog No. 2 (LRH-A2) and chorionic gonadotropin (HCG). The injection dosage of female snakehead fish is as follows: HCG (1200IU/kg) + LRH-A2(10 μ g/kg) by one-needle injection; the male fish of the channa argus is HCG (900IU/kg) + LRH-A2(8 mu g/kg), the first injection is 1/3, and the interval between two needles is 18 h.

In the induced spawning period, the water temperature is controlled to be 25-26 ℃, the effect time of the snakeheads is 21 hours, the effect time of the snakeheads is 40 hours, and in order to ensure the synchronism of spawning and insemination, the induced spawning of the snakeheads is started about 19 hours ahead.

The rest of the procedure was the same as in example 1. The hybrid snakehead fish with excellent growth performance can be obtained.

Example 3

The snakehead hybrid snakehead seedlings bred in examples 1 and 2 were tested.

The method of examples 1 and 2 was used to conduct breeding and to measure the hatchability and emergence rate of the fry of hybrid snakehead mullet.

The snakehead propagation method adopts the following documents: the technical outline of cultivation and artificial breeding of the snakeheads of Julin, Li Yisson, Feng Xiaoyu, Guo shui Rong, Xie nan, Jushu, Jiangsu agricultural science, 2011,39(03): 298-.

The method for breeding the Channa argus adopts the following documents: 34-35 parts of the whole artificial propagation test of the Channa argus in eastern Ling [ J ]. Water conservancy fishery, 2005 (03).

The breeding method of hybrid snakehead adopts the following documents: artificial propagation and fry breeding technology research on hybrid snakeheaded fish [ J ] fresh water fishery, 2010,40(06):56-60.

Randomly selecting 20 groups of data, and performing single-factor statistical analysis, wherein the results are shown in table 1.

TABLE 1 comparison of reproductive performance of hybrid snakeheads with that of existing snakeheads

Note: the shoulder marks of the same row of data are in different lower case letters indicating significant differences (P < 0.05). The same goes for

Hatching rate is multiplied by 100 percent of hatched fry/fertilized eggs; the rate of emergence is equal to the number of fry/fertilized egg of pond fish multiplied by 100%

As can be seen from table 1. The hatchability and the rate of emergence of the two new hybrid varieties are far higher than those of common snakeheads, monthly snakeheads and hybrid snakeheads (the male parent of the snakeheads is multiplied by the female parent of the snakeheads) in the prior art.

2. Ponds with 15 mouths and an area of 1 mu are selected, 5 snakehead fries are respectively put in the ponds, and production tests are carried out (the fry breeding and adult fish breeding in the embodiment 1 of the invention are adopted). In the initial stage of the test, fingerlings (generally 5-8cm) with the average weight of 10.34 +/-0.24 g are selected, 5000 fish seeds are put in each mu for fish breeding, and the period is 5 months. After finishing the fingerlings, 2000 fingerlings with uniform sizes are selected from the corresponding ponds and put into 1 mu of pond, and adult fish culture is started with a period of 10 months. And (3) when the 2 stages are finished, randomly fishing 100 snakehead rows and weighing through a net spreading mode, and comparing the growth conditions of different stages. After adult fish culture is finished, randomly selecting 20 snakeheads in each pond for dissection, and detecting the body indexes, wherein the calculation method of the detection indexes is as follows: visceral index (VSI) visceral weight/total fish weight 100%. The results are shown in Table 2.

TABLE 2 comparison of growth Performance of hybrid snakehead fish with that of existing snakehead fish

Through production tests, the average weight conditions of 5 snakeheads in the fish species and adult fish are compared, and the average weight of the two new hybrid species of the mullet hybrid snakeheads is obviously higher than that of common mullet snakeheads, mullet heads and the existing mullet hybrid snakeheads; meanwhile, the bait coefficient at the end of the adult fish stage is obviously lower than that of the snakehead, the Channa argus and the existing hybrid snakehead. In addition, the number of edible parts of the fish body can be seen through the visceral index, and as can be seen from the above table 2, the visceral index and the fullness of the two bred snakehead hybrid snakeheads are obviously lower than those of the existing snakehead hybrid snakeheads and are close to those of the common snakeheads and the snakeheads, which indicates that the edible parts of the existing snakehead hybrid snakeheads are the fewest snakeheads because the visceral masses are larger, and the edible parts of the snakehead hybrid snakeheads are more.

3. And (3) randomly selecting 10g of fish flesh on the back of the dissected 20 snakeheads in the step (2) for detection, wherein the muscle nutrient content and the muscle amino acid composition are respectively shown in tables 3 and 4.

TABLE 3 comparison of the nutrient contents of the muscles of hybrid snakehead with those of common snakehead and monthly snakehead (wet weight%)

TABLE 4 comparison of amino acid composition of hybrid snakehead with common snakehead and monthly snakehead muscles (wet weight%)

Note: tryptophan is not detected because it is destroyed during the hydrolysis process. Table symbol indicates umami amino acids.

Table 3 shows that the muscle nutrient components of the two new hybrid species of the mullet hybrid snakeheads are different from those of the common mullet and the mullet, wherein the content of crude protein is obviously higher than that of the common mullet and is not much different from that of the common mullet, but is still slightly lower than that of the mullet. The total amino acid and the umami amino acid of the common snakeheads are lower than those of the two new hybrid varieties and the snakeheads in the composition of the amino acid, wherein the total amino acid and the umami amino acid of the snakeheads are the highest in 4 fishes, but the difference with the snakeheads of the two new hybrid varieties is not obvious. The nutrient level of the fish meat mainly depends on the content of protein and amino acid in the muscle, so that the nutrient level of the snakehead of the new hybrid variety of the invention is close to that of the Channa argus, but is far higher than that of the common snakehead and the currently cultured snakehead hybrid snakehead.

Claims

1. A method for crossbreeding snakeheads and snakeheads is characterized by comprising the following steps:

(1) parent breeding: in autumn of the previous year of propagation, the Channa argus and the Channa argus are selected as parents for hybridization breeding, the breeding is carried out in a stocking pond, and the breeding is transferred to a greenhouse for breeding when the water temperature begins to decrease in 11-12 months;

(3) parent selection: selecting the Channa argus and Channa argus with mature gonads as parents in 5-6 months;

(4) artificial hastening parturition: carrying out artificial induced spawning on the snakeheads and the snakeheads selected in the step (3), and carrying out advanced induced spawning on the snakeheads;

(5) artificial insemination: adopting dry fertilization;

(6) hatching management: hatching the fertilized eggs, and hatching the fry to obtain the fry;

(7) fry rearing: and (5) after hatching the membrane, culturing until the fry can grow to 1-2cm, and then transferring the fry into a pond for culturing.

2. The method for crossbreeding snakeheads and snakeheads according to claim 1, wherein the snakeheads selected in the step (1) are preferably selected to be snakeheads with the age of more than 1 foot, no disease or injury and the body weight of more than 100g, and the snakeheads selected are selected to be snakeheads with the age of more than 2 feet and the body weight of more than 600g as parents for crossbreeding.

3. The method for the hybridization breeding of the snakeheads and the monthly snakeheads according to claim 1, which is characterized in that in the step (2), the parents of the snakeheads and the monthly snakeheads are transferred to a greenhouse for intensive cultivation in 3-4 months in the second year; feeding high protein compound feed combined with fresh fish and shrimp as bait, flushing water to promote gonad maturation, controlling water temperature in the greenhouse by heating facility at 20-25 deg.C during cultivation, and inspecting parent gonad development condition.

4. The method for crossbreeding snakeheads and snakeheads according to claim 1, wherein parents with mature gonads are selected in the step (3) to carry out crossbreeding, and male fishes of snakeheads and snakeheads are selected: the genital pore is narrow and is slightly protruded, the tail end is slightly red, and the semen flows out when the two sides of the abdomen are slightly squeezed; selecting female fishes of snakeheads and monthly snakeheads: the abdomen is enlarged and soft, the middle of the abdomen is faced upward, obvious grooves appear, the outline of the ovary is obvious, and the genital orifice is slightly red and swollen and protruded.

5. The method for crossbreeding snakeheads and snakeheads according to claim 4, wherein in the step (3), the female weight of the snakeheads is more than 200g, and the male weight is more than 300 g; the female body weight of the snakehead is more than 750g, and the male body weight is more than 1000 g.

6. The hybridization breeding method for snakeheads and snakeheads according to claim 1, characterized in that the artificial induced spawning in the step (4) is carried out by using a luteinizing hormone releasing hormone analogue No. 2 and chorionic gonadotropin, and the injection dosage of the snakehead female fish is as follows: HCG (1000-1200IU/kg) + LRH-A2(10-15 μ g/kg); the male fish dose is HCG (500-600IU/kg) + LRH-A2(5-7.5 μ g/kg); injecting the female fish and the male fish by one needle; the oxytocic drug dosage of the female fish of the snakehead is as follows: HCG (1500-; the male fish dose is HCG (750) -900IU/kg) + LRH-A2(7.5-9 μ g/kg). The two-shot method is adopted, 1/3 in the first injection dose is separated from the two needles by 15-18 h.

7. The method for the hybridization breeding of the snakeheads and the monthly snakeheads according to claim 1, wherein the water temperature is controlled to be 25-26 ℃ during the induced spawning period in the step (4), the effect time of the snakeheads is 19-22 hours, the effect time of the monthly snakeheads is 38-42 hours, and the early induced spawning of the monthly snakeheads is carried out.

8. The method for crossbreeding snakeheads and snakeheads according to claim 1, wherein the dry fertilization process adopted in the step (5) is that after the effect period is reached, the abdomen of female snakeheads is firstly slightly pressed, and the eggs are collected in a clean washbasin; rapidly extruding the abdomen of the male snakehead, dripping the semen into a washbasin, continuously stirring by using feathers to uniformly mix the semen and the ovum, adding a sperm activating solution after uniformly mixing, rapidly stirring, removing upper-layer foam, and cleaning for 2-3 times, wherein all the insemination operation is completed within 3 min; if the hybridization dry fertilization method of the male channa lunata and the female channa argus is adopted, the method is the same.

9. The snakehead and snakehead hybridization breeding method according to claim 1, wherein in the step (6), the hatching is specifically that fertilized eggs are placed in a hatching cylinder and are hatched by micro-flow water, and meanwhile, the bottom of the hatching cylinder is oxygenated by a microporous nano disc to provide sufficient dissolved oxygen to promote hatching; controlling the water temperature at 27-28 ℃ during hatching, and obtaining the fry after 36-42h of membrane emergence after fertilization.

10. The snakehead and snakehead hybrid breeding method according to claim 1, wherein the snakehead and snakehead hybrid breeding method is characterized in that after the fry are hatched and membrane is removed in the step (7), the yolk sac disappears and the fry can swim smoothly, at the moment, the fry start to be opened to feed, the fry need to be transferred to a breeding pond from an incubation cylinder for first-stage breeding of the fry, plankton feeding is adopted until the fry are removed from the membrane for 10 days, the fry can grow to 1-2cm, the fry can be transferred to the pond for breeding, the fry can be continuously bred in two stages, and two snakehead hybrid snakeheads with excellent growth performance can be obtained after the fry are bred and adult fish are bred.