CN110074023B - Navodon septentrionalis fry breeding method - Google Patents

Abstract

The invention relates to a method for cultivating takifugu rubripes fries, which belongs to the field of aquaculture. The method fully utilizes natural life habits and biological characteristics of the globefish, solves the problems of palatable bait of small-caliber variety of fry such as globefish, death of adherent larvae, low fry breeding efficiency and the like, can provide high-quality fries for various breeding modes, can save time and labor, effectively reduce cost, and can provide powerful support for large-scale fry breeding, fine breed breeding, germ plasm preservation, artificial breeding, proliferation and releasing and the like of the globefish.

Description

Navodon septentrionalis fry breeding method

Technical Field

The invention relates to the technical field of aquatic product fry breeding, in particular to a takifugu rubripes fry breeding method.

Background

Navodontopterodon globefish (Navodonstrentonalis Gunther) belongs to the order Takifugu, family Takifugu. Jiangzhe and Fujian are called peeled fish and elephant fish; pig fish, skin crafted fish, bread fish, and grilled fish are called Shandong, Liaoning, and Hebei, etc. Belongs to warm water bottom layer fish, has poor feeding property, favors clustering and has weak swimming capability.

In recent years, the ecological environment and germplasm resources of the navodon septentrionalis are greatly influenced by various adverse factors such as over-fishing and water area pollution, so that the resource quantity of the navodon septentrionalis is gradually reduced, the market price is gradually increased, and the special marine products have the tendency of gradually fading out of the market. Fry breeding and artificial breeding of the thamnaconus modestus are highly regarded, and some regions develop traditional coal-fired boiler temperature rise seedling raising, pond culture and the like, but because the biological characteristics of the thamnaconus modestus are not fully understood, the energy consumption is high, and the production effect is not ideal.

At present, the thamnaconus modestus is mostly cultivated by adopting artificial fertilization and other modes, the situations of high energy consumption, great technical difficulty, high operation cost and large human and property investment exist in the fry breeding process, and the resource quantity of the degraded important fishery resource variety is difficult to recover in time.

Disclosure of Invention

The invention aims to solve the technical problem of providing a method for cultivating the navodon septentrionalis fry, which fully utilizes the natural life habit and the biological characteristics of the navodon septentrionalis, solves the problems of difficult solution of initial feed, high death rate in the middle period, low emergence rate and the like in the breeding of the navodon septentrionalis fry, and overcomes the problems of high cost, high energy consumption, high labor intensity and the like in the prior art.

The invention is realized by the following technical scheme:

a method for cultivating takifugu rubripes fries is characterized by comprising the following steps of parent fish selection and reinforcement, natural spawning and collection, incubation, bait culture and reinforcement, fry cultivation and commercial fries:

1) parent fish selection and reinforcement:

the parent fish is required to select 2-3-year-old natural sea area wild Navodon septentrionalis which is large in individual, good in body color, free of damage, deformity and disease, strong in activity, robust and active, the selection and cultivation of the Navodon septentrionalis parent fish are started from the middle ten days of 3 months to the last ten days of 5 months, the number of the parent fish cultured in each 10 water bodies is 80-100, and the male-female ratio is 2:1 or 3:1;

keeping the temperature in the parent fish culture pond at 18-22 ℃, the daily water exchange amount is 100-200%, naturally illuminating, adjusting the illumination intensity to be within the range of 1000-2000 lx, avoiding direct light, and removing residual bait and excrement at the bottom of the pond by using a bottom suction device in the morning and evening;

feeding baits including fresh oysters, common mussels, ruditapes philippinarum, chlamys farreri, clamworms and hawk crayfish in the parent fish strengthening culture, wherein the feeding rate is 2-6% (weight ratio);

2) naturally spawning and collecting:

during the reinforcing period of the parent fish, the gonad development degree of the parent fish is periodically checked, the abdomen of the parent fish with better development is expanded, the outline is obvious, and the parent fish has soft and elastic hand feeling; when the pressure is light, milk white semen or orange eggs flow out, and when the eggs grow to the extent, an egg collecting device can be placed in the parent fish pond;

the collection method of the fertilized eggs comprises the following steps: placing the ovum collection device in a parent fish pond, taking out the ovum collection device after the parent fish spawns for 12 hours by self, and transferring the collected fertilized ovum into a culture pond for incubation;

3) hatching:

incubation conditions of fertilized eggs of navodon septentrionalis: the water quality is clean and pollution-free, natural seawater is disinfected by sand filtration and ultraviolet sterilization, water is not changed during incubation, the seawater is cultivated in a cultivation pond, the initial water depth is 40-50 cm, the water temperature is 19-22 ℃, the salinity is 32-33 per thousand, the pH is 7.8-8.2, uninterrupted micro-aeration is carried out, the Dissolved Oxygen (DO) of the cultivation water body is kept to be more than or equal to 5mg/L, and the illumination is 1000-2000 lx; observing the development condition of the fertilized eggs under a microscope every day, and timely removing the dirt on the water surface; the water temperature is slowly increased to 23-26 ℃ along with the development of the newly hatched fries, and the temperature is maintained in the subsequent cultivation process;

after the fertilized eggs are completely hatched, the egg collecting device is timely fished out of the culture pond, during the period, the continuous micro-aeration is carried out, after the fry are hatched for 48 hours, initial bait is thrown, the daily water addition amount is 10-15% (volume ratio) in the initial period, and then the water change amount is gradually increased along with the growth and development of the fry until the continuous running water culture is carried out all day long;

4) bait culture and reinforcement:

the bait used for breeding the takifugu rubripes fries is as follows: SS rotifer → artemia nauplius → artificial micro-particle compound feed → shellfish meat, timely switching bait and adjusting feeding amount according to development and growth conditions of thamnaconus modestus;

reinforcing bait: culturing SS rotifers with chlorella solution and schizochytrium for 6-12 hours in an enhanced manner, collecting the rotifers and feeding the rotifers;

collecting and shelling the incubated artemia nauplii, putting the artemia nauplii into a new incubation barrel, adding 30 g of schizochytrium limacinum powder and other trace nutrient elements into each water, carrying out strong aeration reinforced culture for 6-12 hours, and then feeding;

5) and (3) seedling cultivation:

firstly, water environment control fry cultivation requires fresh and stable water quality, fresh water is gradually added to the water depth of 120cm 5-8 days after the fries are opened, a water changing mode at the same temperature is adopted, the water changing rate is 10-20%, the water changing amount is gradually increased along with the growth of the fries, the water changing rate is increased to 50% at the age of 30 days, and the water changing rate is gradually increased to 50-100% along with the growth of the fries and the increase of food intake later; the water temperature is controlled to be 18-26 ℃, the daily change of the water temperature is lower than 1 ℃ along with the gradual rise of the growth and development of the larvae, the pH value is 7.0-8.2, and the Dissolved Oxygen (DO) is more than or equal to 5mg/L, so that the normal growth of the fry is ensured; culturing for 35-40 days, timely separating and pouring the fish fries into ponds according to the juvenile fish culture density, and transferring the fish fries to intermediate culture;

illumination control is performed to ensure that illumination is controlled below 5000lx, preferably 2000 lx-3000 lx when the navodon septentrionalis offspring seeds are cultivated through illumination control, light is forced to be uniform and soft, and strong light and direct light are avoided;

thirdly, in the water changing method, when the fry is hatched for 30 days and no illumination is available at night, a bottom siphon small net cage water changing mode is adopted after the fish school is dispersed, and a small-caliber pipe siphon method is adopted in daytime to avoid the adhesion of the fry to the wall; replacing a large net cage for water change when the whole fry reaches 0.8-1 cm, and culturing the fry by adopting normal running water or a culture mode of 50-100% water change when the whole fry reaches more than 2 cm;

feeding bait in proper amount every day according to the full degree of fry intestines after the fry of the navodon septentrionalis is hatched for the first time in the feeding method, feeding the fry once every morning and evening, keeping the rotifers in the water body to be 8-10/ml all the time, feeding the fry at fixed points in a fish swarm dense area according to the gathering behavior of the fry in the daytime, adding chlorella or concentrated chlorella liquid into a pond every day to keep the water color light green, and keeping the concentration of the chlorella in the pond to be 10 multiplied by 10⁴～30×10⁴ind/ml；

Fifthly, after the bait is converted and SS rotifers are fed for 15-20 days, the feeding amount of artemia nauplii is increased, the rotifers and the artemia are fed for 5-7 days at the same time, the artemia are observed to be ingested by all fish fries, the intestinal tracts of the fish fries under a microscope are orange, feeding of the rotifers can be stopped, and meanwhile, chlorella adding is stopped; feeding the artemia at a feeding density of 2-3/ml; feeding the mixed feed when the fry reaches 2.5-3 cm; in the bait conversion process, a small amount of feed is fed for a plurality of times at fixed points and at fixed time, and domestication and culture are gradually carried out; continuously feeding artemia or fresh shellfish meat while feeding the compound feed until all fish fries are suitable for eating the compound feed, stopping feeding the artemia, feeding 5-8 times every day, feeding 8% -15% of the fish weight in the feed amount every day, sucking the bottom in the morning and evening, and removing the granular bait scattered at the bottom of the pond;

dividing the pond when the body length of the fry reaches 3-5 cm; the fish weight is 5-8 g/tail, and the culture density is 200-300 tail/m³The breeding density of the fry is between 20 and 40 g/tail and is between 100 and 150 tails/m³；

6) And culturing the commercial fish fries with the body length of more than 5cm in an intermediate culture pond, a seawater pond or a seawater net cage, and entering a commercial fish culture stage.

Compared with the prior art, the invention has the beneficial effects that:

1. compared with the traditional fry breeding method, the method fully utilizes the biological characteristics of the Navodon septentrionalis, utilizes natural seawater treated by sand filtration, disinfection and the like, does not need a boiler to heat the seawater, and embodies the green fry breeding concept; the parent fish bait and the initial bait for the larval fish both use fresh and live baits or workshop culture baits, and obviously improve the quality of eggs of the parent fish and the hatchability of fries on the basis of keeping sufficient nutrition supply; the use of compound feed is reduced, a good aquaculture water environment is maintained, so that the daily water change amount of the aquaculture pond is directly reduced, the wall-attached death and water flow impact of seedlings are avoided through the water change mode of the small net cage at the bottom, the death rate is reduced, and the survival rate of the seedlings is increased. In conclusion, the fry breeding cost can be greatly reduced, the quality and the quantity of the fries are improved ecologically and efficiently, and good economic benefits are created.

2. Compared with the breeding of fish fries with non-viscous eggs, the breeding habit of the Navodon septentrionalis is clarified, the egg collector is placed in a parent fish pond, fertilized eggs can be conveniently and efficiently collected, the step of utilizing the incubator to hatch in the past fish fry breeding is omitted, and after the hatching is finished, empty egg shells attached to the egg collector can be directly taken out, so that the operation step of removing the shells is omitted. The collected inseminated eggs can achieve the effects of synchronous development and incubation by taking and placing the ovum collector regularly, the specification and the size of the fry are relatively uniform by matching with proper water temperature and culture conditions, and high-quality healthy fries can be cultured, and the hatchability and the survival rate of the fries are improved.

3. The emergence rate can be different due to different species, and experimental observation shows that the globefish fry are gathered into groups in the daytime and are scattered in the evening, the tropism and the day and night habits of the globefish fry can be fully utilized, bait feeding is carried out when the globefish fry are gathered into groups, and light can be utilized to lure and feed the globefish fry at night, so that the effects of saving bait, reducing bait-pulling energy consumption, increasing the ingestion rate and improving the survival rate and the emergence rate of the globefish fry are achieved. Simultaneously, utilize this habit, can carry out the drainage at night or under the dark condition of light, the mode of adding water the next day, the little net cage in bottom trades the water mode and can also discharge the dead rotifer, impurity residual bait etc. of bottom of the pool, improves and breeds the interior water environment of pond, not only can prevent and avoid the fry to adhere to the wall and die, has still reduced the mortality and the morbidity of seedling.

4. The method is feasible in production practice, saves labor, time, labor, worry and money in the fry breeding process, can be applied to fry breeding work of other similar fishes, and is particularly suitable for breeding fish varieties such as parent fishes producing viscous and semi-viscous eggs or small newly hatched fries and small mouth cracks.

Detailed Description

The following examples are given to illustrate the technical solutions of the present invention, but the scope of the present invention is not limited in any way by the examples.

Example 1

A method for cultivating pufferfish fries comprises the steps of parent fish selection and reinforcement, natural spawning and collection, incubation, bait cultivation and reinforcement, fry cultivation and commercial fries, and comprises the following specific steps:

1. parent fish selection and reinforcement:

in 2016, in 5 months, 216 tails of wild parent fishes are collected from sea areas near the Hujia wharf in the Qingdao and the Fenghuang island, and are artificially domesticated to live 187 tails. The parent fish has a standard length of 25.2-32.5 cm and a weight of 244-574 g. The difference between the male and female of the takifugu obscurus in the non-breeding period is not obvious, and the male and female are difficult to identify from the appearance. Through anatomical comparison of the sexually mature parent fishes, the sexually mature parent fishes can be identified from the appearance and body type simply and visually, and the parent fishes have large length-width ratio and are male fishes and small female fishes. The number of fish fries cultured in a 10-square glass fiber reinforced plastic parent fish culture pond is 80-100, the male-female ratio is 2: 1-3: 1, the temperature is kept at 18-22 ℃, the daily water exchange amount is 100-200%, residual bait and excrement at the bottom of the pond are removed by a bottom suction device in the morning and evening, natural illumination is used, the illumination intensity is adjusted within the range of 1000-2000 lx, and direct light is avoided.

Feeding and feeding baits such as fresh oysters, common mussels, ruditapes philippinarum, chlamys farreri, clamworms, hawk crayfish and the like in the parent fish strengthening culture, wherein the feeding rate is 2-6%. Practice proves that the bait has good ingestion, and proper amount of physique enhancer and vitamins can be added into the bait to enhance the physique of parent fish and improve the quality of sperms and ova. After spawning is finished, bait domestication can be carried out by adopting a method of gradually reducing the amount of live baits and simultaneously increasing the feeding amount of the compound feed, and parent fishes continuously adapt to the feeding of the compound feed, so that bait conversion can be gradually completed. After 25 days of temporary culture and cultivation and reinforcement of the parent fish, the gonads of the parent fish gradually mature.

2. Naturally spawning and collecting:

the spawning cycle time of the thamnaconus modestus is about 1 month, and the thamnaconus modestus is in a batch multiple spawning-discharging type. After artificial domestication, nutrition strengthening and reproduction regulation, the parent fish naturally spawns.

The collection method of the fertilized eggs comprises the following steps: 1. putting parent fish with well developed gonads into a spawning pond, putting an ovum collector (a multilayer three-dimensional plastic plate or a screen basket) at the bottom of the pond, allowing the parent fish to spawn and fertilize by self, and taking out the parent fish from the spawning pond after spawning for 12 hours; 2. placing the ovum collector in a parent fish pond, taking out the ovum collector after the parent fish spawns for 12 hours by self, and transferring the collected fertilized ovum into a culture pond for incubation; 3. and (4) manually using a soft net to fish naturally-produced fertilized eggs attached to the bottom and the wall of the parent fish pond.

The 1 st method for egg collection is easy to cause damage and stress reaction to parent fish, and the 3 rd method causes mechanical damage to fertilized eggs to a certain extent, and influences the hatchability and survival rate. In practice, the 2 nd egg taking mode is adopted, when the large-scale egg laying insemination is carried out, the eggs are taken by using the multilayer three-dimensional plastic plates, one period is 12 hours, and the eggs can be continuously and uninterruptedly taken in a production workshop.

In this example, parent fish of Navodon septentrionalis begins to lay eggs in 6 months. Collecting fertilized eggs for seed breeding in 6 months, 10 days to 7 months and 15 days, wherein the spawning period is about 1 month.

3. Hatching:

incubation conditions of fertilized eggs of navodon septentrionalis: cultivating the seeds in a breeding pond with the depth of 4 mx 3 mx 1.2m by using natural seawater disinfected by sand filtration, wherein the initial water depth is 40-50 cm, the water temperature is 19-22 ℃, the salinity is 32-33 per thousand, the pH is 7.8-8.2, the seeds are subjected to uninterrupted micro-aeration, the Dissolved Oxygen (DO) in a cultivation water body is kept to be more than or equal to 5mg/L, and the illumination is 1000-2000 lx. Observing the development condition of the fertilized eggs under a microscope every day, and timely removing the dirt on the water surface. The water temperature is slowly increased to 23-26 ℃ along with the development of the newly hatched fries and is maintained during the subsequent cultivation process. The incubation time of the thamnaconus modestus is generally more than 3 days when the incubation water temperature is lower than 18 ℃, and the membrane incubation time is 1.5-2 days when the water temperature is kept at 20-22 ℃. And (5) counting the data such as fertilization rate, hatching rate and the like after hatching.

Fertilized eggs are generally incubated within 48-50 hours, egg shells are still left on the egg collector after incubation is finished, and the egg collector is timely fished out from the pool. During the period, the micro-inflation is continuously carried out, the total length of the newly hatched fries is about 2.0mm, the yolk sac is large, and the nutrient substances in the yolk sac are consumed in the early stage. After 48 hours, the mouth crack of the fry is formed, the digestive tract is opened, the mouth is opened for feeding, and the mouth-opened bait can be fed. The daily water addition amount is 10-15% in the initial stage, and then the water change amount is gradually increased along with the growth and development of the seedlings until the continuous running water cultivation is carried out all day long.

4. Bait culture and reinforcement:

the bait used for breeding the takifugu rubripes fries is as follows: SS rotifer → artemia nauplius → artificial micro-particle compound feed (Yubao No. 2, No. 3) → shellfish meat, timely switching bait and adjusting feeding amount according to development and growth conditions of the thamnaconus modestus.

Bait culture: the SS rotifers are propagated and cultured in an animal bait workshop, the fry is propagated to a third-level seed before opening, the culture is fed when the fry is in a logarithmic growth phase, 1-4 eggs are hung below a single rotifer, and fresh yeast and chlorella can be fed when the rotifer is cultured. The artemia nauplii can be hatched for 24 hours by purchasing high-quality artemia eggs under the conditions of illumination of 2000lx and water temperature of 28-30 ℃, collecting the artemia nauplii, removing shells, and feeding after nutrition enhancement is finished.

Reinforcing bait: the rotifer is strengthened, the rotifer belongs to self-cultured pure SS rotifer and does not contain other protozoa and pathogenic bacteria, the rotifer is cleaned and filtered by a 300-mesh silk net before feeding each time, the vitality of the rotifer is examined by a microscope, and the rotifer cannot be fed if the rotifer has poor state or a large number of empty shells die. Placing the cultured healthy SS rotifers at 2m³And adding chlorella liquid and schizochytrium limacinum into the incubation barrel, adding 30 g of schizochytrium limacinum powder into each water body, culturing the rotifers for 6-12 hours in an enhanced mode, and collecting the rotifers for feeding.

And (3) artemia enhancement, namely collecting and shelling the hatched artemia nauplii, putting the collected and shelled artemia nauplii into a new hatching barrel, adding 30 g of schizochytrium limacinum powder and other trace nutrient elements into each water, carrying out strong aeration enhanced culture for 6-12 hours, and then feeding the artemia nauplii.

5. And (3) seedling cultivation:

the efficient cultivation method of the takifugu obscurus fries can solve the main problems that the fry is suitable for initial feeding in the early stage, the fry is easy to adhere to the wall in the middle stage and the conversion of the bait in the later stage is low, and can greatly improve the quality and the emergence rate of the fries by grasping a plurality of key points.

Controlling water environment. The fry cultivation requires fresh and stable water quality, fresh water is gradually added to 120cm in 5-8 days after the fry is opened, a water changing mode at the same temperature is adopted, the water changing rate is 10-20%, the water changing amount is gradually increased along with the growth of the fry, the water changing amount is increased to 50% when the fry is 30 days old, and the water changing rate is gradually increased to 50-100% along with the growth of the fry and the increase of food intake later. The water temperature is controlled to be 18-26 ℃, the daily change of the water temperature is lower than 1 ℃ along with the gradual rise of the growth and development of the larvae, the pH value is 7.0-8.2, and the dissolved oxygen is more than 5mg/L, so that the normal growth of the fry is ensured. Culturing for 35-40 days, timely separating and pouring the fish into ponds according to the juvenile fish culture density, and transferring to intermediate culture of the fries.

② controlling illumination. The Navodon septentrionalis fry is fond of mild light, most of the fries and young fishes gather in the surface layer of the water body, certain selectivity is provided for light intensity, the fries and young fishes gather in bright places at night and in early morning and at dusk when the light is weak, the fries and young fishes gather in dark places when the light is strong in the daytime, and the fries are dispersed in the water and do not gather at night. The illumination is generally controlled below 5000lx during the cultivation of the navodon septentrionalis fry, preferably 2000 lx-3000 lx, the light is required to be uniform and soft, and strong light and direct light are avoided.

And thirdly, a water changing method. The fry just hatched from the globefish is very small, the growth rate of the fry cultured for 10 days is generally not more than 100%, the fry is soft before 30 days, no leather skin coating is formed, the fry is easy to stick to the wall and die in the water changing process, and the like, so that the fry can be changed in a bottom siphoning small net cage water changing mode after the fish school is dispersed, a small-caliber pipe siphoning method can be used in the daytime to avoid the adhesion of the fry, a large net cage water changing mode can be changed when the whole fry reaches about 0.8-1 cm, and a normal flow water culture mode or a 50-100% water changing culture mode can be adopted when the whole fry reaches more than 2 cm.

Fourthly, feeding method. After the fry of the thamnaconus modestus is hatched for initial hatch, proper amount of bait is fed every day according to the full degree of the fry intestines, the bait is fed every morning and evening, the rotifers in the water body are kept at 8-10/ml all the time, the feeding method is implemented according to the gathering behavior of the fry in the daytime, the fixed-point feeding is implemented in a fish swarm dense area, the probability of fry ingestion can be increased, and the ingestion energy consumption is reduced. Simultaneously adding self-cultured living Chlorella or commercial concentrated Chlorella solution into the pond every day to keep the water color light green, and keeping the Chlorella concentration in the pond water at 10 × 10⁴～30×10⁴ind/ml, not only provides bait for SS rotifers, but also can strengthen bait and strengthen nutrition.

Fifthly, converting bait. And after the SS rotifers are fed for 15-20 days, a small amount of artemia nauplii can be fed, the rotifers and the artemia are fed for 5-7 days at the same time, the artemia are observed to be ingested by all fish fries, intestinal tracts of the fish fries under a microscope are orange, the rotifers can stop feeding, and chlorella can also stop adding. The early stage artemia individuals need to be small (the artemia are hatched for 24 hours), the artemia individuals can be increased and strengthened for later feeding along with the increase of the fish bodies, and the feeding density is 2-3/ml. When the fry reaches 2.5-3 cm, the compound feed can be fed. In the bait conversion process, a small amount of feed is fed for a plurality of times at fixed points and at fixed time, and domestication and culture are gradually carried out; the fry is suitable for actively feeding the compound feed. Continuously feeding the artemia or the fresh shellfish meat while feeding the compound feed until all the fries are suitable for eating the compound feed, and stopping feeding the artemia. Feeding 5-8 times every day, wherein the daily feeding amount is 8% -15% of the weight of the fish, sucking the bottom in the morning and evening, and removing the granular bait scattered at the bottom of the pond.

Sixthly, dividing the pool. And when the body length of the fry reaches 3-5 cm, separating the fry into ponds. Along with the growth of the thamnaconus modestus, the thamnaconus modestus needs to be cultured in separate ponds in time, the fry stocking density is reduced from large to small, the size and specification of the thamnaconus modestus in the same culture pond are kept to be neat, the large fishes can be prevented from eating the small fishes, and the feed utilization rate can be improved. The fish has a weight of 5-8 g/tail and a density of 200-300 tails/m³The density of the fry is 100-150 tails/m when the weight of the fry is 20-40 g/tail³。

6. And (3) commercial offspring seeds:

the cultivation time of the thamnaconus modestus from the newly hatched fries to the commercial fries is 50-80 days, and the specification is 5-7 cm. The fry can be cultured in an intermediate culture pond, a seawater pond or a seawater net cage after the body length of the fry reaches more than 5cm, and then the commercial fish culture stage is carried out.

After 40-50 days of seedling culture, 22.6 thousands of active healthy commodity seedlings with the length of 34-78 mm are cultured, and the hatchability, the survival rate and the emergence rate are respectively as follows: 93.1%, 80.6% and 65.6%.

Example 2

This example is substantially the same as example 1 except that the parent fish was of a different batch.

In 6 months in 2017, 317 tails of wild parent fishes are collected from the sea area near the Langya harbor wharf in Qingdao, and 285 tails of the wild parent fishes are domesticated and survive artificially. The parent fish has a specification length of 24.7-35.5 cm and a weight of 215-580 g. The parent fish is temporarily cultured in separate ponds, and the parent fish begins to lay eggs continuously and naturally in the last 6 th of month after the intensive culture for about 7 days because the temperature is higher in the same period in this year than in the previous year. Collecting fertilized eggs for seed breeding in 5-6-20 days in 6 months, wherein the water temperature is 21-24.2 ℃, and the spawning period is about half a month. After 35-45 days of seedling culture, 33.9 thousands of active healthy commodity seedlings with the length of 35-70 mm are cultured, and the hatchability, the survival rate and the emergence rate are respectively as follows: 95.3 percent, 85.8 percent and 72.3 percent.

Claims (1)

1. A method for cultivating takifugu rubripes fries is characterized by comprising the following steps of parent fish selection and reinforcement, natural spawning and collection, incubation, bait culture and reinforcement, fry cultivation and commercial fries:

1) parent fish selection and reinforcement:

the parent fish is required to select 2-3-year-old natural sea area wild Navodon septentrionalis which is large in individual, good in body color, free of damage, deformity and disease, strong in activity, robust and active, the selection and cultivation of the Navodon septentrionalis parent fish are started from the middle ten days of 3 months to the last ten days of 5 months, the number of the parent fish cultured in each 10 water bodies is 80-100, and the male-female ratio is 2:1 or 3:1;

keeping the temperature in the parent fish culture pond at 18-22 ℃, the daily water exchange amount is 100-200%, naturally illuminating, adjusting the illumination intensity to be within the range of 1000-2000 lx, avoiding direct light, and removing residual bait and excrement at the bottom of the pond by using a bottom suction device in the morning and evening;

feeding baits including fresh oysters, common mussels, ruditapes philippinarum, chlamys farreri, clamworms and hawk crayfish in the parent fish strengthening culture, wherein the weight ratio of the bait feeding rate is 2-6%;

2) naturally spawning and collecting:

during the reinforcing period of the parent fish, the gonad development degree of the parent fish is periodically checked, the abdomen of the parent fish with better development is expanded, the outline is obvious, and the parent fish has soft and elastic hand feeling; when the pressure is light, milk white semen or orange eggs flow out, and when the eggs grow to the extent, an egg collecting device can be placed in the parent fish pond;

the collection method of the fertilized eggs comprises the following steps: placing an ovum collection device in a parent fish pond, wherein the ovum collection device is a multilayer three-dimensional plastic plate or a screen basket, taking out the ovum collection device after the parent fish spawns for 12 hours by self, and transferring the collected fertilized eggs into a culture pond for incubation;

3) hatching:

incubation conditions of fertilized eggs of navodon septentrionalis: the water quality is clean and pollution-free, natural seawater is subjected to sand filtration and ultraviolet sterilization, water is not changed during incubation, the seawater is cultured in a culture pond, the initial water depth is 40-50 cm, the water temperature is 19-22 ℃, the salinity is 32-33 per thousand, the pH is 7.8-8.2, the air is filled in a micro mode continuously, the Dissolved Oxygen (DO) of a culture water body is kept to be larger than or equal to 5mg/L, and the illumination is 1000-2000 lx; observing the development condition of the fertilized eggs under a microscope every day, and timely removing the dirt on the water surface; the water temperature is slowly increased to 23-26 ℃ along with the development of the newly hatched fries, and the temperature is maintained in the subsequent cultivation process;

after the fertilized eggs are completely hatched, timely fishing out the egg collecting device from the culture pond, continuously and slightly inflating, feeding initial bait after the fry are hatched for 48 hours, wherein the daily water addition volume ratio is 10-15% in the initial stage, and then gradually increasing the water change amount along with the growth and development of the fry until the fry are continuously cultured in running water all day long;

4) bait culture and reinforcement:

the bait used for breeding the takifugu rubripes fries is as follows: SS rotifer → artemia nauplius → artificial micro-particle compound feed → shellfish meat, timely switching bait and adjusting feeding amount according to development and growth conditions of thamnaconus modestus;

reinforcing bait: culturing SS rotifers with chlorella solution and schizochytrium for 6-12 hours in an enhanced manner, collecting the rotifers and feeding the rotifers;

collecting and shelling the incubated artemia nauplii, putting the artemia nauplii into a new incubation barrel, adding 30 g of schizochytrium limacinum powder and other trace nutrient elements into each water, carrying out strong aeration reinforced culture for 6-12 hours, and then feeding;

5) and (3) seedling cultivation:

firstly, water environment control fry cultivation requires fresh and stable water quality, fresh water is gradually added to the water depth of 120cm 5-8 days after the fries are opened, a water changing mode at the same temperature is adopted, the water changing rate is 10-20%, the water changing amount is gradually increased along with the growth of the fries, the water changing rate is increased to 50% at the age of 30 days, and the water changing rate is gradually increased to 50-100% along with the growth of the fries and the increase of food intake later; the water temperature is controlled to be 18-26 ℃, the daily change of the water temperature is lower than 1 ℃ along with the gradual rise of the growth and development of the larvae, the pH value is 7.0-8.2, and the dissolved oxygen is more than or equal to 5mg/L, so that the normal growth of the fry is ensured; culturing for 35-40 days, timely separating and pouring the fish fries into ponds according to the juvenile fish culture density, and transferring the fish fries to intermediate culture;

illumination control is performed to ensure that illumination is controlled below 5000lx, preferably 2000 lx-3000 lx when the navodon septentrionalis offspring seeds are cultivated through illumination control, light is forced to be uniform and soft, and strong light and direct light are avoided;

thirdly, in the water changing method, when the fry is hatched for 30 days and no illumination is available at night, a bottom siphon small net cage water changing mode is adopted after the fish school is dispersed, and a small-caliber pipe siphon method is adopted in daytime to avoid the adhesion of the fry to the wall; replacing a large net cage for water change when the whole fry reaches 0.8-1 cm, and culturing the fry by adopting normal running water or a culture mode of 50-100% water change when the whole fry reaches more than 2 cm;

after the puffer fish is hatched for the first time and the fries are opened, proper bait is fed every day according to the full degree of the fries, the puffer fish is fed once every morning and evening, the rotifers in the water body are kept at 8-10/ml all the time, the feeding method is implemented according to the gathering behavior of the fries in the daytime, the fixed-point feeding is implemented in a fish school dense area, meanwhile, the chlorella or concentrated chlorella liquid is added into the pond every day to keep the water color light green, and the concentration of the chlorella in the pond is kept at 10 multiplied by 10⁴～30×10⁴ind／ml；

After the bait is converted and SS rotifers are fed for 15-20 days, the feeding amount of artemia nauplii is increased, the rotifers and the artemia are fed for 5-7 days at the same time, the artemia are observed to be ingested by all fish fries, the intestinal tracts of the fish fries under a microscope are orange, feeding of the rotifers can be stopped, and chlorella adding is stopped; feeding artemia which are incubated for 24 hours in the early stage, and feeding the reinforced large-size artemia individuals with the feeding density of 2-3 artemia/ml along with the increase of the fish body in the later stage; feeding the mixed feed when the fry reaches 2.5-3 cm; in the bait conversion process, a small amount of feed is fed for a plurality of times at fixed points and at fixed time, and domestication and culture are gradually carried out; continuously feeding artemia or fresh shellfish meat while feeding the compound feed until all fish fries are suitable for eating the compound feed, stopping feeding the artemia, feeding 5-8 times every day, feeding 8% -15% of the fish weight in the feed amount every day, sucking the bottom in the morning and evening, and removing the granular bait scattered at the bottom of the pond;

fourthly, dividing the pond when the body length of the fry reaches 3-5 cm; carrying out cultivation density when the weight of the fish is 5-8 g/tail is 200-300 tails/m, carrying out cultivation density when the weight of the fish is 20-40 g/tail is 100-150 tails/m;

6) and culturing the commercial fish fries with the body length of more than 5cm in an intermediate culture pond, a seawater pond or a seawater net cage, and entering a commercial fish culture stage.