Grass carp (Ctenopharyngodon idellus) is a kind of fish belonging to Cyprinidae.[14]Grass carp is long, slightly cylindrical, with flat tail, round belly and blunt head;The mouth end position is arc-shaped, no need;The upper jaw is slightly longer than the lower jaw;The eye is small, and the eye diameter is smaller than the snout length;The hypopharyngeal teeth are comb shaped with transverse grooves on the side of the teeth;Scale medium size, lateral line scale;The body is tea yellow, the abdomen is gray, the chest and pelvic fins are slightly grayish yellow, and the other fins are dark.[15]It is named because its staple food is water and grass.[16]
Grass carp are distributed in the Yangtze River and Pearl River water systems and affiliated lakes, reservoirs and ponds in China.[17]Rivers and lakes mostly inhabit in plain areas, and generally inhabit in the middle and lower layers of water and near shore areas with many aquatic plants.Grass carp are lively by nature, swim quickly, and often hunt in groups.It feeds on zooplankton in the larval stage and insects, earthworms, algae and duckweed in the juvenile stage, which is a typical herbivorous fish.[18]4-5 years old is the spawning population, and mid to late May is the peak breeding period.[19]
Grass carp is warm in nature and sweet in taste;It can calm the liver, dispel wind, activate arthralgia, stop malariaWarm stomachThe role of;It also contains rich unsaturated fatty acids, which are very beneficial to blood circulation and cardiovascular patients. It is a health product for warming and tonifying deficiency.Grass carp is rich in nutrients, making it edible.[20]
It was named (Li Shizhen, Ming Dynasty) because it eats grass.《Literary Expositor》Also known as grass carp, the same as grass carp（《Song rhyming dictionary》）；Also known as 鯶.Guo Pu of the Jin Dynasty noted that "today's fish are as big as trout".Li Shizhen said that "its nature is soothing, so the grass carp is called" chui ", commonly known as grass carp".Northeast famous grass root fish;Beijing famous grass wrapped fish;Hebei Province is known as "thick fish" because of its wide and thick head.Because of its light color, it is also called white grass carp.[13]It is named because its staple food is water and grass.[16]
History of origin
Grass carp is a kind of fish in the north warm temperate zone, monsoon climate, the Great Plains, and large rivers and lakes. It is about the time when the Himalayas began to rise in the late Neogene Pliocene and the eastern plains of China produced monsoon, monsoon and large rivers and lakes.[4]
Breeding history
Grass carp has been cultivated for more than 1700 years, but before that, it was eaten or sold after natural fry from rivers were raised in ponds. It was only after the success of artificial propagation of four major domestic fishes in 1958 that all artificial cultivation was realized.[4]
morphological character
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Grass carp (Ctenopharyngodon idellus) is a kind of fish belonging to Cyprinidae.[14]Dorsal finⅢ-7；Gluteal finⅢ-8～9；Pectoral finⅠ-16～18；pelvic finⅡ-8。Lateral squama38～44；Anterior scales of dorsal fin 14-16;Pericaudate scales 14~18.The outer gill rake of the first branchial arch is 14-18.Two rows of hypopharyngeal teeth, 2.4 (5)~5 (4) - 2.Spinal bones 4+40~42.
Grass Carp
The body length is 3.4~4.0 times of the body height, 3.6~4.3 times of the head length, 7.3~9.5 times of the tail shank length, and 6.8~8.8 times of the tail shank height.The head length is 3.0~4.1 times of the snout length, 5.3~7.9 times of the eye diameter, 1.7~1.9 times of the eye spacing, 1.8~2.5 times of the tail handle length, and 1.7~2.4 times of the tail handle height.The tail shank length is 0.8~1.1 times of the tail shank height.
Grass carp is long, slightly cylindrical, with flat tail, round belly, blunt head and no ventral ribs.The head is wide, medium and large, and the front is slightly flat.The snout is short and blunt, and the snout is slightly longer than the eye diameter.The mouth end position is arc-shaped, no need;The upper jaw is slightly longer than the lower jaw;The end of the maxilla extends below the nostril.The posterior lip groove is interrupted with wide spacing.The eye is small, and the eye diameter is smaller than the snout length;The eyes are wide and slightly convex, and the eye spacing is more than 3 times of the eye diameter.The gill hole is wide and extends forward to the lower part of the posterior edge of the anterior operculum;The operculum is connected with the isthmus;The gorge is wide.The scale is medium in size, lateral scale, round.The front part of the lateral line is curved, and the back part is straight, reaching the caudal fin base.[15]
The dorsal fin has no hard spines, and its outer edge is flat and straight. It is located above the pelvic fin, and the distance from the starting point to the caudal fin base is closer than to the snout end.The anal fin is located at the lower back of the dorsal fin, the distance from the starting point to the caudal fin base is close to the distance to the starting point of the pelvic fin, and the end of the fin does not extend to the caudal fin base.The pectoral fin is short and blunt at the end. The distance from the end of the fin strip to the starting point of the pelvic fin is greater than 1/2 of the length of the pectoral fin.The caudal fin is shallow bifurcated, and the upper and lower leaves are about the same length.
The gill rakes are short and small in number.The hypopharyngeal bone is equal in width, slightly hooked, and the posterior arm is slightly larger.The hypopharyngeal teeth are flat on the side, in a "comb" shape, with grooves on the side, oblique and straight crown surface, and a narrow groove in the middle.The swim bladder is 2-celled, the anterior chamber is thick and short, the posterior chamber is longer than the anterior chamber, and the end is pointed.The intestine is long and coiled for many times, and its length is more than twice of the body length.The peritoneum is black.
The body is tawny, the abdomen is grayish white, the scales on the side of the body are grayish black, the pectoral and abdominal fins are grayish yellow, and other fins are light.[5][15]
Habitat environment
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Grass carp mostly inhabit rivers and lakes in plain areas, and generally inhabit the middle and lower layers of water and near shore areas with many aquatic plants.[18]
Life habits
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Grass carp is a typical herbivorous fish. It is lively, swims quickly and often forages in groups.Grass carp feed on zooplankton in the larval stage, larvae, earthworms, algae and duckweed in the juvenile stage, and grass carp also eat some meat, such as earthworms, dragonflies, etc.Overwintering in the deep water of the main stream or lake.In reproductive season, the parent fish has the habit of swimming backward.[5-6][18]
Grass Carp
Distribution range
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Grass carp is widely distributed in China from Heilongjiang to Yuanjiang, Yunnan (except Tibet and Xinjiang).[5]It has migrated to Asia, Europe, America, Africa and other countries.[6]
Grass carp is naturally distributed in China, Russia and Bulgaria. In China, it is mainly distributed in the Yangtze River, Pearl River water systems and affiliated lakes, reservoirs and ponds.Grass carp in the Heilongjiang River system entered the Heilongjiang River system from the river plain area when Nenjiang River was connected with Liaohe River and Bohai Sea before the PlioceneAihui, Xingkai Lake is slightly above Qiqihar;The grass carp in the Pearl River system may have expanded from the lower reaches of the Yangtze River and Qiantang River to the Pearl River system, reaching Quanzhou, Du'an, Baise, etc. when the sea level was 100 meters lower than the current level in the glacial period and the Taiwan Strait was a low plain.[17]
Grass carp was first introduced from China in Malaysia in the 1980s. Grass carp were successively introduced to 93 countries, some from China, such as India, the United States, Hungary, Mexico, and some from other importing countries, such as Sudan (imported from India), Sweden (imported from Hungary), which has formed a population in Malaysia, the United States, and other countries.The original purpose of introduction was to control aquatic plants and aquaculture, such as the United States, Egypt, India, etc.[4]
Distribution map of grass carp[2]
Reproductive mode
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Natural reproduction
Grass carp is generally sexually mature at the age of 4, with the earliest age being 3, and spawning population at the age of 4-5.Mature female individuals weigh more than 5 kg.Breeding season of grass carp andsilver carp、bigheadIt is basically the same period, that is, from April to July. The breeding period varies from north to south in China. It is from April to June in the Yangtze River, later in northeast China, and the mid to late May is the peak breeding period.During the breeding season, pearl stars appear on the pectoral fin strips of the parent fish, which gives a rough feeling when touched by hand.Grass carp eggs are relatively large, about 5 mm in diameter, and belong to floating eggs.[5][7][19]
The spawning place of grass carp is generally at the confluence of the main stream of the river, the deep channel water area on one side of the meander, and the river section with sudden contraction on both banks.Grass carp can lay 300000 to 1.38 million eggs at a time.After the fertilized egg swells due to water absorption, its diameter can reach about 5mm, and it can float along the water.[8]
The parent fish artificially bred by grass carp mainly come from the original breeding ground, rivers, lakes and reservoirs.The parent fish from natural waters are selected from large-sized grass carp, and grass carp with normal body color, complete fins and scales, no injury and disease, lively swimming, and strong physique are used as backup parent fish. After intensive cultivation, the production is accelerated.The parent fish from the artificial breeding environment are usually healthy grass carp that have reached the sexual maturity age and are in the breeding age in ponds or ponds.In the process of collecting and transporting parent fish, the operation should be careful, and the nets and tools should be selected to avoid injury to the fish.[9]
Intensive cultivation of parent fish
The prenatal cultivation stage is an important stage for the transformation of parent fish nutrients into gonads. During the reproduction of grass carp, the intensive cultivation of parent fish is the key to the success of artificial reproduction. The quality of parent fish cultivation will directly affect the maturity of gonads, the rate of spawning, the rate of fertilization and hatching of eggs.The breeding management of parent fish mainly includes the following five important links.[9]
Water temperature control
The parent grass carp is extremely sensitive to the fluctuation of water temperature, which will affect the development and maturity of gonads. Therefore, it is very important to control the water temperature during the breeding of parent grass carp, and large water temperature fluctuations must be avoided.[9]
Regularly flush and inject new water
Make the pool water circulate, and create a flowing water environment artificially, which can stimulate the gonad development of the parent fish.After March, the fish pond will be flushed once a week, and in April, it will be flushed twice a week for 2-3 hours each time.[9]
Adequate oxygen content
It is necessary to master the dissolved oxygen status in the water of the breeding pool to prevent the floating head of the parent fish. Insufficient oxygen content in the water will inhibit the gonadal maturation of the parent fish. During the breeding process of the parent fish, the oxygen content can be increased by injecting new water, opening an oxygen increasing machine or using drugs.[9]
Suitable stocking density
Improper stocking density and matching ratio of parent fish will reduce the reproduction level, and too high stocking density will affect the gonad development of parent fish.The stocking density is calculated according to the body weight, and can be mixed or single raised. In order to make full use of the water body, it is best to match with the backup parent fish of different species.Generally, parent fish (including assorted fish) can be stocked at 100~150 kg/mu, and can reach 200 kg/mu in good conditions. When the average parent fish of grass carp reaches more than 200 kg/mu, the breeding level of grass carp will be seriously reduced.[9]
Bait feeding
Feed feeding is also very important in the process of parent fish cultivation. The natural feed in the parent fish pond cannot fully meet the nutritional requirements of the parent fish, so additional feed is needed.The added feed can be one or more kinds of grass feed, or can be mixed with pellet feed with high protein content.The formula feed of grass carp must contain high protein content and avoid carbohydrates and lipids, otherwise it will lead to abdominal fat deposition, which will affect the development of gonads.The feed for grass carp pre production cultivation is mainly grass feed, supplemented by refined feed. The grass feed is mainly Sudan grass, ryegrass, fan grass, rape, Chinese cabbage, malt, etc.[9]
Estrogenic oviposition
Urging time:The main determinant of the time of labor induction is water temperature.The suitable temperature for artificial reproduction of domestic fish is 22~28 ℃, the optimum temperature is 24~26 ℃, and the feasible temperature for artificial reproduction of grass carp is 18~31 ℃.The breeding period of grass carp is usually from the end of April to June every year. The same region also varies according to the geographical environment and altitude. The place with high altitude is later than the place with low altitude, and the parent fish in the reservoir is later than the parent fish cultivated in the pond.The specific time for inducing labor needs to be determined comprehensively according to various physiological indicators of grass carp.At the later stage of parent fish cultivation, as the gonad gradually matures, the grass carp diet begins to decline. At this time, the suitable breeding time can be preliminarily determined by observing the shape of grass carp feces. Combined with the observation of parent fish and egg digging identification, the breeding time can be basically determined. The feces of grass carp generally change from large to small, from long to oval, from loose to firm before spawning. At the end of the change,It is the suitable time for grass carp to induce labor.When the gonad of the parent fish reaches maturity, if it is not stimulated in time, the gonad will degenerate. Therefore, it is necessary to grasp the time of induced labor.
Selection of spawning parent fish:The reproductive capacity of parent fish is positively correlated with age, body length and weight. The optimal reproductive age of grass carp is 5-10 years old, and the weight of mature female grass carp is 5-10kg.The male female ratio should be different depending on the breeding method used in each field. Generally, the male female ratio of full artificial breeding method is 2:1~1.5, while the male female ratio of semi artificial method is 1:1~1.5.In the process of artificial reproduction of grass carp, the female and male parent fish can make preliminary selection based on the phenotypic characteristics. The male grass carp has thicker and longer fins, which open naturally in a sharp knife shape;In the reproductive season, when the gonads are well developed, there are dense granular processes called "pearl stars" on the inner side of the pectoral fin and the gill cover, and the hand feels rough.The mature male parent fish is soft at a finger from the genital pore, and the genital pore is slightly purple. You can press the abdomen gently with your hand. If there is thick milky white semen flowing out, it will disperse when entering the water.The mature female fish can be selected for shape observation and egg digging observation. The pectoral fin of female grass carp is thin and short, slightly fan-shaped in natural opening, generally without star chasing, or only a few protrusions at the end of the pectoral fin, without rough feeling.Through the appearance observation, it can be seen that the abdomen of the female fish is swollen and elastic, the outline of the ovary is obvious, the genital pores are loose, the abdomen is upward, the side of the body has the outline of the ovarian mass droop, the middle of the abdomen is concave and hollow, when you pat the abdomen with your hand, there is a feeling of looseness, and the arrangement of scales below the abdomen is loose;By digging eggs, we can see that the eggs are neat, large and full, and the nucleus is offset, which indicates that the parent fish is mature.
Selection of oxytocic agents:The oxytocic agent is mainly exogenous hormone. By stimulating the pituitary gland to further synthesize and release FSH, increasing the concentration of FSH in the fish, it can strengthen the transformation process of nutrition in the body, accelerate the development process of gonads, and promote the early and smooth birth of the parent fish.The oxytocic drugs used for artificial reproduction of grass carp mainly include fish pituitary gland (PG)Chorionic gonadotropin(HCG), luteinizing hormone releasing hormone analogue series (LRH-A) and dioxone (DOM), etc. These drugs can induce grass carp to spawn when used alone or in combination.
Injection mode of oxytocic agent:The oxytocin needs to be dissolved into a suspension with normal saline before it can be injected into the fish body with water. The injection site is divided into two types: intracavitary injection and intramuscular injection. The effects of the two are the same.Intracavitary injection can also be divided into two ways: intrathoracic injection and intraperitoneal injection. The intrathoracic injection is in the scale-free depression at the base of the pectoral fin of the fish. The needle is inserted at an angle of 45~60 ° to the body axis in front of the fish, with a depth of about 1cm. It should not be too deep, otherwise it will hurt internal organs;The intraperitoneal injection is at the base of the pelvic fin, the injection angle is 30-45 °, and the depth is about 1-2 cm.The intramuscular injection is usually carried out at the muscular plump place under the dorsal fin, and the needle is inserted into the muscle 1~2 cm forward along the scale for injection.The injection of oxytocin can be divided into one injection and two injections. At present, the second injection method is mostly used, because the first injection of the second injection method has the function of ripening, its oviposition rate, oviposition amount and fertilization rate are high, and the oestrus time of parent fish is relatively consistent, which is especially suitable for early spawning or spawning when the maturity of parent fish is not enough.When the second injection is used, about 10% of the total amount of oxytocin is injected for the first time, and all the remaining doses are injected 6 to 24 hours later. The lower the water temperature or the worse the maturity of the parent fish, the longer the interval between the second injection.
Oviposition and fertilization:There are two methods of spawning and fertilization: ① natural spawning and fertilization and artificial insemination.Natural spawning and fertilization is to set up fish nests in the spawning pool before the parent fish is injected with oxytocin. After the injection of oxytocin, female and male fish are put into the spawning pool in a ratio of 1:1~1.5.Before the effect time is reached, stimulate the parent fish with a certain amount of running water. When the effect time is reached, change the running water to the micro running water state, let them naturally spawn and ovulate, and complete the whole fertilization process in the spawning pool. ②Artificial insemination mainly adopts dry method.Dry artificial insemination is to dry an ordinary washbasin, then use a towel to dry the water on the parent fish and fish clip caught, squeeze the fish eggs into the basin, and immediately squeeze the male's semen, and then shake the washbasin in one direction to mix the sperm and eggs, so that they can be fully fertilized.Then measure the volume of the fertilized egg with a measuring cylinder, add water, and move it into the incubation loop or incubation bucket for incubation.[9]
Incubation equipment
The commonly used equipment for fertilized egg incubation includes running water cement pool, domestic fish spawning pool, incubation loop, incubation tank, incubation bucket, cage, etc. The more commonly used equipment are incubation bucket (tank) and incubation loop.
Incubation loop is the main production facility for large-scale seedling cultivation. The common loops in production can be divided into circular and elliptical ones. According to the number of loops, they can be divided into single loop, double loop, three loop, etc. Each loop is composed of water inlet pipe, drainage pipe, filter window, and seedling collecting pipe.The proper density of circular hatching is 1 cubic meter of water to hold 100000 to 150000 fish eggs. The flow rate in the ring is 0.3 m/s. Fish fry can be hatched in 24 to 34 hours. The hatching rate is high and stable, but the cost is relatively high.The incubator can be made of tin, plastic and glass fiber reinforced plastic. It can hold 200~400 kg of water, and 100 kg of water can hatch 200000 eggs. It has the advantages of high density, high hatching rate and easy use.Incubation can be carried out both indoors and outdoors. Generally, indoor incubation has a good effect. Outdoor incubation must take shading measures, and the fertilized eggs should not be directly exposed to the sun, so as to avoid strong ultraviolet radiation killing eggs or causing abnormal embryonic development to produce deformed larvae.[9]
Incubation management
The artificial incubation of fertilized eggs can adopt the hydrostatic incubation method and the flowing water incubation method. The key to improve the hatching rate of fertilized eggs is to do a good job in incubation management.The following six aspects need to be done well in the incubation process of grass carp:
Do a good job in water quality management:During incubation, the pH value of water should be kept at 7.5~8.0. The incubation water must be treated well to keep the water fresh and oxygen rich.
Adjust the water temperature:During the incubation process, the water temperature should be kept stable. Too high, too low or sharp changes in the water temperature are extremely harmful to embryonic development.The incubation temperature of grass carp is 17~32 ℃, and the suitable temperature is 22~28 ℃. Within this temperature range, the higher the water temperature, the faster the development. When the water temperature is 25 ℃, the fry can hatch out of the membrane about 24 hours later.
Ensure sufficient dissolved oxygen: in the whole development process, the embryo stage has the worst hypoxia tolerance, so it is very important to ensure sufficient dissolved oxygen during the incubation process.During the incubation process, dissolved oxygen needs to be detected once an hour to ensure that the dissolved oxygen is more than 4~5 mg/L, so as to keep the water quality fresh and oxygen rich, so as not to affect the fertilized eggs and fry.
Pay attention to removing dead eggs to prevent water mold infection:Dead eggs and fish fry with weak physique are easily infected by water mold under low water temperature and poor water quality, and cotton like water mold disease occurs. The eggs or fish fry infected with water mold should be removed in time to avoid infecting good eggs or healthy fish fry.
Protect from direct sunlight:Ultraviolet radiation can cause abnormal embryonic development, and shading measures should be taken for outdoor incubation.
Remove the harmful organisms:The copepods and cladocera in the water not only consume a lot of oxygen, but also use their appendages to puncture the egg membrane or directly bite the larvae and embryos, causing a large number of deaths;Small fish, shrimp and tadpoles can directly swallow fish eggs, so they must be completely removed.[9]
Breeding technology
Fry selection
Scientific selection of grass carp is the key to the success and profit of grass carp farming.Therefore, when selecting fry, attention should be paid to their body surface status and moderate size. The same batch of fry cannot be selected from different places. A single species should be selected for stocking in the same pond, but at the same time, other fish such as crucian carp that can purify water quality should be added to prevent the addition of fry with interspecific competition from affecting the growth of grass carp.It can also independently cultivate excellent varieties through cross breeding, or introduce new fry obtained by the Institute through biological engineering for trial breeding.According to the climatic conditions in Shandong, China, it is generally better to breed before and after the Spring Festival.[10]
Pond Selection
Grass carp farming also has certain requirements for ponds and water quality.Only by ensuring a good growth environment, can the healthy growth of fry be ensured.Appropriate breeding sites should be selected according to relevant breeding regulations to avoid wasting water resources or causing incalculable pollution to the surrounding environment.One of the most important conditions for grass carp farming is to ensure adequate water sources.In the breeding process, we should ensure that there is sufficient power and complete power supply facilities.In general, a microporous aerator with a power of 2 kW and an automatic feeder should be equipped within the scope of the 8 mu pond.Convenient transportation conditions are available to ensure that large cultured fish can be shipped out for sale immediately, and improve the survival rate of grass carp in the process of sale.
After selecting the geographical location of the fishpond, the fishpond should be thoroughly cleaned and disinfected.The control of fish pond environment generally achieves four points: ① ensure good water quality without pollution, and meet the requirements of normal growth and development of grass carp; ②The water depth of the fishpond is generally about 1.5~1.8m, which may fluctuate according to the actual situation, but it is generally not recommended that the water depth be less than 1.5m, and the pond should not be less than 2m; ③According to the experience of fishermen in many places, the ratio of length to width of fishpond is 5:3, which is the best; ④At the bottom of the fish pond, a certain amount of sludge that can maintain the water in the fish pond and promote the mineralization of organic matter can be considered. This environment is conducive to the growth of grass carp.
The best water quality for culture is between 6.6 and 7.8 pH, and the neutral or weakly alkaline water quality is most conducive to the growth of grass carp. Overacidification will cause the epidermal tissue of grass carp gills to be eroded, which will increase the prevalence of grass carp;However, long-term alkaline conditions will inhibit the respiratory system of grass carp and affect other physiological functions such as the digestive system, which is not conducive to the growth of grass carp.Therefore, it is very important to choose the water quality environment suitable for grass carp growth.The oxygen content in the water also has a certain impact on the growth of grass carp. Therefore, it is necessary to ensure sufficient oxygen content to prevent large grass carp populations from dying in large quantities due to insufficient oxygen supply.[10]
Feed requirements
Granular feed with protein content of about 32% is generally required.In order to facilitate regular feeding, the automatic feeder is used to feed four times at 8:00 am, 11:00 pm, 14:00 pm and 17:00 pm respectively.Feeding times can be flexibly handled according to weather conditions, water quality and fish feeding conditions.Avoid overeating of grass carp. In high temperature climate, strictly control the feeding amount, and stop feeding when 80% of the food is full. Pay attention to removing the unused feed every day to avoid affecting the water quality.Regular feeding of soybean meal instead of plankton will not damage the water quality for grass carp farming, but also can be used as feed to further provide nutrition.[10]
Disease and insect control
Disease prevention technology
When grass carp grows to 70-150g and has a body length of 10-20cm, the fingerling is prone to acute infectious diseases.Reasonably control the number of fry, avoid excessive density causing hypoxia and negative impact on water quality, damage the growth environment, and then facilitate the generation and spread of diseases, resulting in a large number of fry deaths.Under general conditions, the optimal condition is to control the density of fry between 220000 and 300000 fish per 1000 square meters. If this value is exceeded, the prevalence rate will increase significantly.Therefore, it is necessary to catch grass carp in a timely manner, and keep the fish quantity in the pond at 1/2K at all times, which can ensure the fastest production speed of grass carp and certain economic benefits.If conditions permit, breeding fish species in rice fields will also have a greater impact on the survival of fish species.[10]
Pond cleaning and disinfection
To provide a good environment for grass carp to grow and avoid disease.Generally, the water is changed at dusk, and the water source is changed every 3 days or so. Adding 3~5cm of water each time can ensure that the dissolved oxygen in the water is increased, promote the appetite of fry and improve their basic metabolic capacity, and then improve their resistance to bacteria, so that they can grow healthily.Periodically disinfect the pond with high-quality photosynthetic bacteria to avoid the outbreak of infectious diseases in the poor water quality environment due to harmful substances such as hydrogen sulfide and nitrogen oxide produced by grass carp feces in the pond.[10]
Fish fry disinfection and vaccine injection
In sunny days, fish seeds should be put in 3% sodium chloride solution or potassium permanganate solution containing 0.01~0.02% for 3 minutes before putting in, which can kill parasites or pathogens on the surface of fish to a certain extent.Then put the sterilized fish seeds into the cage, inject 0.2m triple vaccine for each 125g or so of fish seeds, and then put them into the fish pond.It can prevent common diseases such as grass carp gill rot disease, hemorrhagic disease and enteritis by increasing the fish's own immune system, and ensure the healthy growth of grass carp species.[10]
Feed disinfection
Generally, 1 kg of fish feed needs to be disinfected with 5~10 ml of chlorine containing bleaching powder solution.[10]
Disease treatment
Most grass carp will die if they suffer from the common, highly infectious and high mortality diseases enteritis, gill rot and red skin disease.At this time, feed should be stopped to avoid further affecting the water quality and expanding the disease infectivity, and the addition of chlorine containing disinfectant should also be stopped to avoid further death due to low resistance of grass carp during illness.At this time, the feed containing Wuping that can treat grass carp enteritis and canjieling should be put into the diet 3 to 5 days later or the relevant drugs should be directly put into the diet. After 7 days, the dosage should be further increased until the death of grass carp is reduced, which can reduce the dosage of medicated feed or fish drugs, gradually increase and restore the normal feed, and at the same time, pay attention to the growth state of grass carp population at all times.If grass carp gets sick due to parasites, it can be released to the Insect Killer King once every two days, and the fish can be seen to recover in about a week.[10]
Economics:Grass carp is an excellent cultured fish and one of the four traditional freshwater cultured fish in China because of its simple diet, wide source of feed and fresh and tender meat. It has high economic value.[5]
medical:Traditional Chinese medicine believes that grass carp is warm in nature, sweet in taste, and enters the liver and stomach meridians.It has the effects of warming stomach, activating arthralgia, stopping malaria, calming liver yang, dispelling wind, treating arthralgia, nourishing yin and improving eyesight.Deficiency of body and weak stomach, malnutrition, hyperactivity of liver yanghypertension, headache and tinnitus, etc.[12][20]
Edible:Grass carp is rich in unsaturated fatty acids, which is beneficial to blood circulation. Eating it regularly can play a role in protecting cardiovascular and cerebrovascular diseases. It is a good food for cardiovascular patients.Grass carp is rich inseleniumElement, which can resist aging and keep your face healthy when taken regularlytumourIt also has a certain preventive effect;Grass carp is nutritious, rich in a variety of trace elements and vitamins. It is a good tonic for people who are weak and have poor appetite.Grass carp is rich in nutrients, making it edible.[12][20]
