Sturgeon rearing methods
Sturgeon is a benthic fish, diet is very narrow, is a carnivorous fish, in the river mainly to some small or slow-moving benthic animals for food, in the ocean the main fish for food, crustaceans, mollusks are less. Sturgeon larvae in the estuary mainly feed on benthic fish genus Snake Kun and nymphs and scaly shrimp and clams, etc., spawning period generally stop eating. Chinese sturgeon is a kind of warm water fish adapted to a wide range of water temperature, in artificial culture conditions, the survival of Chinese sturgeon water temperature is 0 ~ 37 ℃, the growth of suitable water temperature of 13 ~ 25 ℃, the optimal growth of water temperature of 20 ~ 22 ℃. Parental sturgeon suitable for spawning water temperature of 17 to 24.5 ℃. The best incubation water temperature for eggs is 17～21℃. After winter, when the water temperature drops to 9 ~ 6 ℃, the sturgeon intake is very little, growth stagnation, and even the phenomenon of weight loss. Around spring, the water temperature gradually rose to 10 ~ 13 ℃, began to feed a small amount, slow growth. After the Qingming, the water temperature rose to more than 15 ℃, feeding began to be active, growth accelerated. When the water temperature reaches 33 ~ 38 ℃, the sturgeon can not normal activities. In the vertical swimming stage, the fry have strong phototropism. After turning to benthic, phototropism disappears. General light intensity on the baby, young sturgeon cultivation does not have a significant impact, but try to avoid the summer bright light directly into the pool and cause a sharp rise in water temperature, the breeding pool above the sun-shading facilities should be set.
Sturgeon appearance
Adult Chinese sturgeon body large and heavy, male body generally weighs 68-106 kg, female 130-250 kg, because they are the largest fish in the Yangtze River, so there is also? The king of the Yangtze River? The name. Chinese sturgeon body was fusiform, head pointed kiss long, four kissing whiskers in front of the mouth, the mouth in the ventral surface, there is retractable, and can be stretched into a tube, the body is covered with five rows of longitudinal rows of bony plates, the back of a line, the side of the body and the ventral side of the two rows, each row has a spine-like protrusion. Sturgeon is a rare ancient fish left behind by the Mesozoic Era 150 million years ago, it is between cartilage and hard bone, the degree of ossification of the skeleton is generally reduced, the central axis of the uncemented elastic spine, no vertebrae, and most of the cartilage shells along with the cranium are not ossified. The caudal fin is crooked, the even fin with a broad base, and the dorsal fin opposite the anal fin. The ventral fin is located anterior to the dorsal fin, the bases of the fins and the caudal fin are spiny scaled, the intestine is equipped with spiral flaps, the anus and cloaca are located near the base of the ventral fin, and the opening of the oviduct is remote from the ovary.
Sturgeon growth and reproduction
Sturgeon is a large migratory fish. Normally, the Chinese sturgeon inhabits the coastal continental shelf zone from the west coast of North Korea in the north to the southeast coast of China in the south. After living in the ocean for 9?18 years, the gonadal development is close to maturity, they will migrate to the Yangtze River in groups, arriving in the upper reaches of the Yangtze River in Sichuan Yibin area and the lower part of the Jinsha River to reproduce. Every summer and fall, gathered at the mouth of the Yangtze River, upstream to the upper reaches of the Yangtze River Jinsha River spawning, and young sturgeon down the river to the East China Sea, the Yellow Sea in deep water to grow. In the spawning group, the age of the male is generally 9-22 years old, and the female is 16-29 years old. Chinese sturgeon spawning volume is also very large, a female sturgeon once can produce millions of roe, only the survival rate is not high, and finally into the fish is still a minority. After spawning, the female parent fish soon began to descend the river. Spawned eggs adhere to the bottom of the river above the rocks or gravel, in the water temperature of 17-18 ℃ conditions, fertilized eggs about 5-6 days and nights of hatching. Just out of the membrane of the young fish with a huge yolk sac, shaped like a tadpole, drifting along the water, about 12 to 14 days later began to feed. Then the spring, young sturgeon gradually descending the river, May-August appeared in the mouth of the Yangtze River around Chongming Island, after September, the body length has reached 30 centimeters of young sturgeon one after another to leave the mouth of the Yangtze River shallow shoals, into the sea to cultivate the growth of the sturgeon. Chinese sturgeon life expectancy of up to 40 years.
Sturgeon disease control
A, egg mold disease
1, symptoms and causes of the disease The surface of the egg grows yellowish-white hairy flocculent, and in severe cases, the eggs look like a ball in the water. The cause of the disease is the eggs parasitized with water mold and mycobacteria and other aquatic fungi, common species of silk water mold, flagellated mycobacteria and so on. This disease occurs in the artificial incubation stage of fertilized eggs.
2, prevention and control methods are mainly to improve the fertilization rate of eggs, remove bad eggs and unfertilized eggs, to prevent their decay and then pollute the water; followed by 500 grams per cubic meter of water concentration of malachite green can be used to wash the eggs for 15 minutes.
Second, water mold disease
1, symptoms and causes of the disease is due to mechanical trauma to the fish body, the affected area infected with water mold. In severe cases, the fish are slow to act, emaciated, and do not feed, until they die.
2, prevention and control methods There are two main prevention and control methods: one is to use a concentration of 35-50 grams per cubic meter of water body of malachite green and 1% of the salt water mixed solution immersed in 20-30 minutes, there is a certain degree of efficacy; the second is to control the onset of the disease during the seedling by raising the temperature of the water, the water temperature range of 25 ℃ or more, the best is 28-50 ℃.
Third, hemorrhagic disease
1, symptoms and causes of the disease mainly occurs in the larval stage of sturgeon, caused by aeromonas, has a strong infectious, and the onset of rapid, fast spreading, and the mortality rate is also very high.
2, prevention and control methods During the cultivation of seedlings, every 5-10 days with chlorine dioxide or furazolidone and other drugs for disinfection, and regularly add antimicrobial drugs in the feed to prevent, as well as in the feed to add B vitamins, such as vitamin C, vitamin E and so on to improve its immunity.
Fourth, bacterial enteritis
1, symptoms and causes This disease is caused by bacteria. Symptoms are bleeding in the abdomen and mouth, redness and swelling of the anus, and wasting of the fish.
2, prevention and treatment methods Feed with bait containing 0.2% dysentery, continuous feeding for 5-6 days can be cured.
V. Swollen mouth disease
1, symptoms and causes This disease occurs more in the juvenile stage of sturgeon. It is caused by bacteria, mainly due to feeding spoiled bait. Signs of the disease are swollen mouth, surrounded by congestion, red and swollen excretory orifices, inactivity, sometimes accompanied by water mold disease.
2, prevention and treatment methods Fish out the sick fish in time, remove the residual bait, change the injection of new water, regularly disinfect the feed table to ensure the quality of feed.
Six, trypanosomiasis
1, symptoms and causes The pathogen is trypanosomes. Diseased fish are slow to act, the body is bent in the water in the shape of ?L? or ?S?, often lying on the bottom of the water, can't feed, body color is dark, lusterless, and sometimes rotate sharply up and down in the water, if not treated in time, the disease will die in 3-5 days after the onset of the disease.
2, prevention and treatment methods The main treatment method is to add 20-40 international units of penicillin G ammonia salt in 5 kg of water to the bath, once a day, each time for 2 hours; the first two days of the amount of 40 international units of medication, after the third day of the amount of 20 international units of medication, about 7 days or so can be cured, the early cure rate of up to 100%.
VII, rotifers
1, disease and etiology The pathogen is rotifers. Because of the pathogen in the fish body and gill rakers parasitized too much and cause the fish body weak, slow swimming, do not feed, slow growth, and in severe cases a large number of deaths.
2, prevention and control methods Soak in 5% salt water for about 1 hour, and then take the running water to feed a better efficacy; in addition, can also be used to 15% -25% concentration of formalin solution immersion, but can not use copper sulfate.
Eight, oblique tube worm disease
1, disease and etiology The pathogen is oblique tube worm. When the pathogen is parasitized in large quantities in the fish body, mouth and gills, it will cause the sick fish to be irritable and restless, the body surface is blue-gray film-like, and the black pigment in the mouth and eyes increases.
2. Prevention and control methods There is no effective treatment, the main measure taken is to transfer the sick fish into the flow pool to feed, the mortality rate can be reduced to less than 4%.
Nine, small melon worm disease
1, symptoms and causes of the disease is also known as white spot disease. The pathogen is the small melon worm. Signs of the disease are: in the naked eye observation can be found in the gill filaments and fins outside a large number of spots, serious spots were flaky. The diseased fish become thin day by day, the ability to swim is weakened and restless, loss of appetite. When observed under the microscope, white dots can be found in the form of thick bubbles, covered with a white mucous membrane layer. Because of the small melon worm infested fish skin and gill tissues, to fish tissue cells for nutrition, causing fish tissue necrosis, hindering respiration, and ultimately lead to death.
2, prevention and control methods 50 grams per cubic meter of water concentration of formalin solution immersion has a certain efficacy; can also be cultivated during the fry to raise the water temperature to 25 ℃ or more, preferably 28-30 ℃ to control, the effect is better.
Ten, three generations of worm disease
1, symptoms and causes The cause of the disease is feeding the unsterilized daphnia. This disease mainly occurs in the fry stage, the onset of fish around the mouth and gill congestion, the fry were anoxic floating head.
2, prevention and control methods with a concentration of 0.25% of the crystal trichlorfon soak the fish body has a good effect.
Eleven, the horse-necked fish lice disease
1, symptoms and causes The pathogen is a horse-necked fish lice disease. This disease occurs more on the Chinese sturgeon. The pathogen is parasitized on the fin base of the fish body, anus, nasal cavity, pharynx and esophagus, especially gill arches, mouth and other parts of the most common.
2, prevention and treatment methods are generally used to artificially remove the pathogen, and in the affected area coated with antimicrobial ointment; or put the sick fish into 5% salt water immersion for 1-2 hours, but also has a good effect.
XII, hepatic encephalopathy
1, disease and etiology This disease occurs in the sturgeon fry stage, the fish weight 15-20 grams, body length of 15-20 cm. The cause of the disease is toxic additives in the feed. The color and body surface of the fish are normal, no obvious disease, occasionally the front of the head and the front of the muzzle of the fish's ventral epidermis off, the back is pink, the fish have jumping phenomenon in the early stage of the disease, swimming or swimming alone, decreased appetite; later in the state of coma, stop eating, and then died one after another. Anatomy found that the liver was purple, brown, gray, belly erosion, gallbladder normal, no food in the intestine, kidney, spleen and heart normal. The brain tissue of the sick fish is necrotic and eroded.
2, prevention and treatment methods Add lactic acid or lactosorbide in the feed has a good therapeutic effect. For the still not serious sick fish, can be added to the feed on the fish liver damage is not serious antibiotics, such as neomycin, kanamycin, vancomycin and so on.
XIII, epicardial abscess disease
1, symptoms and etiology of the fish body color is normal, the surface of the body in addition to the heart without other symptoms, the appearance of the liver is slightly enlarged, its color by the size of the individual and the degree of bruising point of different degrees of impact, the individual is larger than the black, the small is red, or local appearance of gray-red. The heart is irregularly bumpy and verrucous in appearance, with the ventral surface ranging from white to red, and the arterial bulb red. The anterior part of the heart of the larger fish is gray, and the posterior part is purplish red; the atria of the smaller individuals are enlarged. The foregut of the diseased fish is empty, and the hindgut has more food. The appearance of the intestinal wall, kidneys, gills, spleen, brain and other organs is not abnormal. Diseased fish decline moderately in the early stages of the disease. Scattered or solitary swimming, the later period is slow swimming, stop eating so that death.
2, prevention and treatment methods Because the pathogen is unclear, there is no effective treatment. The main preventive measure is to feed artificial cultivation of water worms or reduce the drugs added to the feed.
XIV, epicardial fat weaving
1, symptoms and etiology There is no obvious pathological changes in the body surface of the sick fish, the dissection can be seen to have a serious lipoatrophy, the color of the surface of the heart is grayish brown to black. Microscopic observation of tissue sections, the damaged cells can be seen around the blood vessels to the center of the concentration, or banded along the edge of the epicardium adipose tissue distribution, severe cases of inflammatory cells infiltrate a large number of tissues, tissue hyperplasia, the fat is replaced by inflammatory cells and hyperplasia, and adipose tissue below the myocardial layer of the myocardium did not see any abnormality. Adipose tissue cell necrosis. This disease is seen only in high stridor. The cause of the disease may be a nutritional imbalance or excessive fat intake, but it is also believed that the lack of vitamin E and trace elements in the feed.
2, prevention and control methods The main preventive measures are to improve the quality of feed to meet the vitamin and mineral requirements
XV, black body disease
1, symptoms and causes of the disease The body of the sick fish is black, thin and weak, the abdomen is thin. Anatomy shows that there is no food in the stomach and the intestines are translucent and filled with yellowish mucus. The cause of the disease is due to abnormal metabolism or malnutrition. This disease mainly occurs in the specification of 8-12 centimeters of juvenile fish stage, the harm is not great.
2. Prevention and control methods Improve the water quality conditions, the use of running water culture; or move the sick fish to another pool, switch to nematodes or better nutritional feed.
Sixteen, potbellied disease
1, symptoms and etiology The abdominal cavity of the sick fish is enlarged, and the abdomen floats upward on the surface of the water, and the swimming is weak. Anatomy can be seen in the stomach more food, gas, air bubbles in the intestine. It is thought to be caused by malnutrition or aeromonas.
2, prevention and control methods Improve water quality conditions, reduce the breeding density, the use of running water breeding methods, add haloperidol 2% -6%, or dry yeast 8% -12%, or rhubarb 3% to the feed, 5 days for a course of treatment, if you find that the fish feces become dilute, it should be timely to reduce the amount of rhubarb.
XVII, erythema
1, symptoms and etiology of the disease occurs in the stage of young fish. Blood-red dotted plaques appear on the front, or lower, or both sides of the yolk sac and the back of the sick fish, and the lower part of the tail end. Sick fish float on the surface of the water, swim slowly, usually from the onset of the disease to the time of death is only about 10 days. The cause of morbidity may be caused by water fleas, shrimp bites, or in the hatching process caused by excessive water flow, non-infectious.
2. Prevention and control methods Thoroughly remove water fleas and other hostile organisms, and reasonably control the speed of water flow during incubation to avoid injury to the young fish.
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