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Rainbow Trout Culture Technology
First, the biological characteristics of rainbow trout? Rainbow trout, commonly known as carp, is a species of Scorpionoidea, currently has 86 countries and regions introduced breeding. (1) Morphological characteristics Rainbow trout is long-spindle shaped, kisses round, small and round scales, pale or dark gray on the back and head, silvery white on the lower abdomen. There are scattered black spots on the body's side, back of the body, and fins. Sexually mature individuals have a rainbow-like purple-red ribbon along the lateral side of the body (this is called rainbow trout) extending to the base of the caudal fin. Rainbow trout is ovoid, 4 to 7 mm in diameter. Yolk yellow, orange, orange or red. Yolk sac long diameter 5 ~ 9 mm, width 3 ~ 6 mm. After 26 days of fertilization (water temperature at 12 °C) hatched, larvae vary in total length with the size of the eggs, usually 15 to 18 mm. The mouth opened, the hernia formed, and the cartilages of the dorsal, anal, and caudal fins began to appear. After hatching on the 23rd (water temperature at 12°C), the yolk sac absorbed 2/3 and the larvae began to float. Floating larvae 18 to 28 mm, fins in addition to pelvic fins, ventral posterior and caudal fins have disappeared. The number of fins basically reaches a certain number. Subsequently, 5 to 13 black puppies appeared on the side of the body. When the body length is 15 cm, dark spots disappear and are replaced by purple-red rainbow bands. (2) Living habits Rainbow trout are cold-water fish and require growth in water quality clarification, with gravel bottom and oxygen-rich flowing water. Their living water temperature is 5～24°C, and the suitable water temperature is 7～18°C. The optimum growth water temperature is 13-18°C. In the range of suitable water temperature conditions, rainbow trout fed strongly and grew rapidly, and the body can maintain a good metabolic state. When the water temperature in the living environment is lower than 7°C or higher than 20°C, the rainbow trout feeds cease, and the body fails to die. In natural waters, if the amount of water is sufficient and the amount of dissolved oxygen is sufficient, the water temperature above 24°C can still be tolerated, while under the conditions of the farm, the water temperature of 22°C or so will be lethal. Rainbow trout is a fish with positive and negative flow and hi oxygen. The stimulation of water flow can not only accelerate the metabolism of the body, but also can take away the excrement. The fresh and oxygen-rich water should be continuously supplied to meet its oxygen demand. . The suitable flow rate for rainbow trout is 2 to 3 cm/s. The amount of dissolved oxygen in rainbow trout to water is generally required to be above 5 mg/l. For rainbow trout to grow well, the best dissolved oxygen in water is above 6 mg/l, and the appetite above 9 mg/l is strong and grows quickly. When the dissolved oxygen in water is less than 5 mg/L, the respiratory rate of rainbow trout is faster, and the breathing is difficult to feel. When it is lower than 4.3 mg/L, the fish is dense in the water injection department and it lasts for a long time. The top of the fish head appears yellow and the lid is covered. Outside, this is the rainbow trout "floating head", at the same time death; below 3 mg / l, suffocation and a large number of deaths, the value of the summer rainbow trout's lethal point. • Rainbow trout prefers clean and transparent water. Suspended matter in the water can cause breathing difficulties. When it is severe, it can suffocate. Feeding in the mixed water stops and growth is blocked, resulting in death. Juveniles are particularly sensitive to turbidity, and turbid water in storms and floods can cause increased mortality in juveniles and juveniles. In addition to temperature and oxygen, rainbow trout has certain requirements for water quality indicators. Although rainbow trout live in water with a pH of 5.5 to 9.2, the optimum pH range is 6.5 to 6.9. The adaptability to salinity increases with the growth of individuals. Juveniles can grow in 0.5% to 0.8% salinity water. Fish can grow in 1.2% to 1.4% salinity water, usually over 35g individuals. The transition of brackish water can adapt to seawater life. Rainbow trout like to cluster, swim faster, fierce feeding, often jumped over the water to compete for food. (3) Diet and growth Rainbow trout is a carnivorous fish that feeds terrestrial and aquatic insects, beetles, shellfish, small fish, and fish eggs. It also eats leaves and seeds of aquatic plants. Juveniles are mainly zooplankton and zoobenthos, such as Cladocera, Trichoptera, Coleoptera, and other aquatic insects. The annual feeding of rainbow trout, even during the spawning period, also predated as usual. Under feeding conditions, rainbow trout can feed artificial compound feed well. The food intake of rainbow trout is often increased or decreased with changes in water temperature, dissolved oxygen, and other ecological conditions. The growth of rainbow trout varies greatly depending on the water temperature, environmental conditions, and feed amount. Rainbow trout grows throughout the year under suitable ecological conditions. Under the condition of water temperature of 14°C, the body weight can reach 100-200 g for one full year, and the body weight can reach 400-1000 g for two years, and the body weight can reach 1000-2000 g for three years. At a water temperature of 9°C, the body weight can reach 40-50 grams in one year, and the body weight can reach 200-300 grams in two years, and it can reach 800-1000 grams in three years. Rainbow trout life can generally be 8 to 11 years. (d) breeding rainbow trout male sexual maturity is generally 2 to 4 years of age, female sexual maturity in 3 to 5 years of age. Normally sexually mature males are mostly 2nd instar and females are mostly 3rd instar. Rainbow trout spawning water temperature is generally 4 ~ 13 °C, the optimum water temperature is 8 ~ 12 °C. Spawning occurs once a year, and the amount of fleshes varies with age and individual size, ranging from 1500 to 3500 capsules. Eggs are yellow, round, and sink. • Mature broodstock should be selected as a spawning ground with gravel sediment, water quality clarification, and rapid water flow. Females excavate spawning pits with caudal fins, lay eggs in pits, protect males from other male fish intrusion, and release ejaculates from male fish after finishing the eggs. After the egg is fertilized, the broodstock is covered with a tail fin and gravel. Reproductive broodstock does not die and can continue to survive and reproduce. The fertilized eggs hatch water temperature range of 6 ~ 13 °C, the optimum water temperature is 8 ~ 10 °C. At a water temperature of 9°C, the incubation period is 36 to 38 days. The hatched fish fry settled between the dark and gravel bottoms, and it was aggregated and fed by the yolk. After 15 to 20 days, when the yolk absorbs 2/3, the pupa starts to inflate, and the fry migrate to the water layer for food. • The spawning season of rainbow trout varies from region to region and varies with water temperature and light. From November to January of the following year in Beijing, it is from December to February of the following year in Taiyuan, Shanxi, and from January to April in Heilongjiang. In water bodies in which the average water temperature is too high, the gonads of rainbow trout can't mature on time, and prolonging the daily light time can advance the spawning period. Artificial Propagation Techniques Artificial breeding of rainbow trout includes several successive stages of broodstock breeding, artificial insemination, hatching, and larval management. (1) Breeding of Broodstock Breeding broodstock that is strong and has strong fertility can obtain ideal egg collection, fertilization, hatching effects, and excellent fish eggs and juveniles. For the broodstock that is to be used as the next year to lay eggs, the annual culturing is started from the spring. The selection criteria for broodstock are robust, disease-free, ages 4 to 5 years old. 1. The environmental conditions for broodstock breeding The fish pond required for broodstock cultivation requires extensive water flow, and the pool is rich in dissolved oxygen. The usual area is 100-300 square meters. The specific situation should be determined according to the direction and scale of development. The water depth is generally 1 to 1.4 meters, and the water injection volume is 0.05 flow per 1000 square meters (ie, 50 liters/second). Suitable incubation temperature limit is 12 ~ 13 °C, the lower limit of 4 ~ 5 °C, 6 months before spawning water temperature should not exceed 12 °C. Cultivating at this temperature is good for obtaining good eggs. If it is cultivated at 5-20°C, it is difficult to obtain high-quality eggs, and the annual growth is in the water of 16-17.5°C. The broodstock grows well but its gonads are immature. In order to facilitate gonad development, the amount of water before sexual maturity should be increased. The suitable density for broodstock breeding is 5 to 10 kg/m2. 2. The relationship between broodstock individual size and fertility? The size of broodstock and its egg size are related to the size and age of the fish. Individual large and older fish have large and numerous eggs. The egg size is also related to the size of the directly hatched larvae, such as 3.5 mm egg diameter, 12 mm of hatched larvae, 7 mm egg diameter, and 20 mm of hatched larvae. In the production of rainbow trout fry, the selection criteria for the age of the egg-collecting probiotics are not the same in different countries. Japan is 2, 3, and 4 years old, North Korea is 4, 5 years old, and China is mostly 2, 3, and 4 years old. 3. The management of broodstock breeding? The artificial reproductive efficiency of rainbow trout is closely related to the broodstock's cultivation and management. In order to cultivate broodstock, special management should be conducted. In particular, attention should be paid to the regulation and management of environmental conditions and feed nutrition. The development of broodstock gonads is accomplished under both external and internal conditions. Whether it is unfavorable external environmental conditions or internal conditions such as lack of feed nutrition, it will affect the gonad maturation of rainbow trout broodstock. The important external factors that affect the development of gonads of rainbow trout broodstock are: ? (1) When the suitable water temperature for the development of gonads in rainbow trout is below 13°C and above 15°C, not only abnormal eggs but also the rate of eye drops can be significantly reduced. When the water temperature is below 4°C, the gonadal development stops and the spawning period is postponed. According to the Japanese Abnormal Jade Aquaculture Test, one month before the spawning period, the broodstock incubation temperature should be kept below 14.5°C, the water temperature is too high, and the occurrence rate of poor broodstock is increased, and the oviparous eye rate is only 30% to 50%. In rainbow trout farms in Linyi City, Shanxi Province, the reproductive effects of broodstock have been affected because of the high natural water temperature that broodstock breeds. (2) Light fish development can be divided into two types according to the different lighting requirements. One is long-day fish, and the other is short-day fish. Rainbow trout is a short-day fish. Within 12 hours of sunshine, rainbow trout develops rapidly in the gonads and slows if the light develops for more than 12 hours. Therefore, to make the rainbow trout gonads develop well, it should be manually controlled within 12 hours as far as sunshine is concerned. The method of manually adjusting the light cycle can control the spawning period. At present, Japan has been able to harvest eggs for the first anniversary, that is, from March to June in spring, from July to October in summer, and from November to February in winter. (3) Sexual stimulation In the natural world, males have a stimulatory effect on the gonads development of females. Therefore, in the breeding process of rainbow trout broodstock, male and female polyculture is adopted, and the stock is maintained one month before spawning. The proportion of males and females raised by broodstock can be controlled at around 4:1. (4) Cultivation of broodstock feed The quality of rainbow trout fish eggs directly affects the fertilization and hatching of eggs. According to the observation and inclusion analysis of rainbow trout roe, they can be divided into three grades: first-class eggs, orange-red, round and full-egg eggs, and the same size of abdominal ovules. Each 100 g of fresh egg vitamin A is in 460 International. Units (IV) and above, carotene more than 20 mg; secondary eggs, orange, round and full of eggs, uniform size, vitamin A in 400 international units (IV); three eggs, light yellow, ovoid Round, not full, uneven in size, Vitamin A below 160 IU. The first and second eggs are high quality eggs, and the third eggs are inferior eggs. Fertilization rate and hatching rate were highest in first-class eggs, followed by second-order eggs, and lowest in third-class eggs. This is due to the fact that carotene and astaxanthin in the yolk have an activating effect on the sperm of the rainbow trout. The quality of rainbow trout fish eggs is related to the quality of broodstock food. The wild rainbow trout that feeds on fish and shrimps, which are mostly high quality eggs, are red or orange. The crude protein used for broodstock's full-priced feed is no less than 38%, crude fat is no more than 6%, and carbohydrates are no more than 12%. Vitamin A is not less than 20,000 international units per kilogram of feed, vitamin D is not less than 2,000 international units, and vitamin E is not less than 75 milligrams. The addition of yeast powder and crawfish powder, shrimp crab powder, crab shell powder and the like contribute to the improvement of the oocytes. Crayfish powder and the like cannot play a role in coloring the egg red pigment. To cultivate gonads with well-developed gonads, a certain amount of nutrient-rich concentrate must be fed. In order to improve the quality of fish eggs, feed formulation should be adjusted accordingly with the different stages of gonadal development to meet the nutritional needs of broodstock at different stages of development. (b) artificial insemination? 1. Male and female identification? Rainbow trout male and female identification, mainly based on body color, head and kiss ends to distinguish. Deep body color, head and mouth large, mandibular upward bending, covering the upper jaw, slightly raised back, abdominal hard, inelastic, vent hole is not prominent, the tip of the kiss for the male fish. The body color is lighter than that of the male fish. The head and mouth are small, the back is not raised, the abdomen is large and soft, elastic, and the gonogenic hole is prominent. The blunt and rounded ends are female fish. 2. 2. Identification of maturity? The progeny of the broodstock that is close to spawning are black in color, the rainbow bands along the sidelines are particularly bright, the appetite is diminished, and there is a phenomenon of chasing each other. Mature female abdomen enlargement and swelling, swelling of the reproductive hole protruding, when the caudal peduncle lifting, both sides of the ovary drooping outline, light pressure on the abdomen with eggs out of the body. Mature males have a darker body color, a rougher surface and a slight decrease in mucus, a softer surrounding genital hole, and light pressure on the abdomen, ie, see the outflow of semen. Usually in the 2 months of the egg collection period, females are not mature at the same time. In order to facilitate timely egg collection and prevent excessive loss of egg mass, it is necessary to conduct a maturity assessment once a week. Eggs should be collected in time and matured according to their maturity. A few tails of male fish can be placed in the female fish pond to promote early maturation of the female fish. The broodstock holding pool may be replaced with a juvenile fish pond or a large pond separated into small ponds. The flow of water shall be maintained at 30 liters/second or more, and the density may be controlled at one tail per square meter. 3. Egg-picking and fertilization Egg-collection is used for extrusion. The squeezer wraps the tail of the female with a towel so that the genital hole faces the ovum and gently presses the abdomen in front of the genital hole. The egg is gently pressed to mature eggs. That is, along with the gonadotropin outflow. The process of squeezing eggs should be gentle and quick, and try not to hurt the broodstock. Artificial insemination is generally used dry insemination, gently dry male body water droplets, squeeze the sperm directly on the eggs, every 5 to 7 female eggs with 2 to 3 tail male sperm can be Or, add 10 ml of pre-empted semen per 10,000 eggs, mix the semen with the eggs in the insemination pot, mix gently with feathers to make full contact with the eggs, then add a small amount of isotonic or clear water Stir quickly and evenly for 1 minute to combine sperm and egg, complete the fertilization process, and then change the water and stir it 1 or 2 times. Wash the excess semen and damaged egg skin. Leave it in water for 30 minutes until the eggs are fully swelled to make the egg membrane. Hardened and flexible, then counted into an incubator for incubation. • The longer the mature eggs are spent in the air, or the longer the fertilization rate is, the lower the fertilization rate will be. Therefore, the egg produced must not be in contact with water before the semen is added, and the time for egg insemination should be within 2 minutes. within. ? During the entire egg collection, sperm collection and insemination and cleaning process, it must be carried out under shading conditions to prevent exposure of fish eggs to direct sunlight. • Brooders are more likely to die if they leave the water for more than 5 minutes. Therefore, they should be placed in a flow pool immediately after picking eggs, and they should be given high-quality, easily-digested food to facilitate the recovery of their broodstock. 4. Counting fish eggs? The water-absorbing eggs are arranged one by one on an angle-iron-shaped egg scale, and the number of eggs arranged within a range of 20 cm in length is measured to obtain the number of eggs per litre. And egg diameter, multiplied by the actual volume can be obtained in the actual number of eggs. (C) Incubation? 1. Characteristics of developmental and sensitive periods of fertilized eggs The number of days from egg fertilization to hatching differs depending on the water temperature, and it takes 46 days at an average water temperature of 7.5°C, ie 343 cumulative temperatures. According to the Heilongjiang Fisheries Research Institute, when the average water temperature is 9°C, the incubation period is about 30 to 38 days. The number of days from the fertilized egg to the eye-opening period is about half of the number of days required for hatching. According to the characteristics of the sensitive period of embryonic development of rainbow trout, it can be divided into six stages: the formation stage of blastocyst, the cleavage stage, the appearance of embryonic ring and embryo shield, the stage of somatic division, the stage of preemergence and the stage of eye opening. (1) The cumulative stage of the blastoderm formation period is 0 to 2, during which period the eggs are fully inflated to form the blastoderm and the oil spheres are concentrated in the animal poles. The external stimulus is not very stable. (2) The cleavage period is 2 to 47 days. During this period, the cells continue to divide, and the splitting spheres continuously become smaller, and the blastocyst cavity appears at the end. It is relatively stable to external stimuli. (3) The emergence period of the embryonic ring and embryo shield is 47-52 days, and the diameter of the blastoderm is enlarged during this period. Increased sensitivity to external stimuli. (4) The somite differentiation period is 52 to 104 days. During this period, the embryonic animal is extremely out-of-plant, and the final blastocyst completely surrounds the yolk sac and the embryo hole is closed. Response to external stimuli is the most unstable. (5) The pre-eye period is 104 to 107 days. Tail buds are formed during this period and blood circulation begins. Sensitivity to external stimuli decreased. (6) The eye period is 107 to 343 days. During this period, the blood circulation is strengthened, and the number of twisting of the embryo body is increased. This period has stable response to external stimuli. ? Therefore, in the first five stages of development of the fertilized eggs should ensure that the development of eggs in a quiet state. The fertilized egg that enters the eye-opening period is called an ovum, and the accumulated temperature is 220 degrees days. Embryonic embryos have the lowest sensitivity to external stimuli and are a safe period of development. At this time, long-distance transport can be performed. 2. Ecological requirements for hatching Sunlight and mechanical shocks have a lethal effect on fertilized eggs, and scattered light also has an adverse effect on the development of eggs. ? Water for incubation requires water quality clarification, no impurities and suspended matter, and suitable water temperature. The optimum water temperature for hatching was 9°C, and the suitable temperature range was 7-13°C. Below this range, the number of hatching days was prolonged, and the hatching effect was not good. Above this range, the hatching eye rate decreased, and the deformed larvae increased. • Incubation water requires sufficient dissolved oxygen. At a water temperature of 10°C, the oxygen consumption per hour per 100,000 fertilized eggs is 260 mg, and the oxygen consumption per 100,000 eggs per hour is 440 mg. Oxygen consumption sharply increased after hatching, which is about 2 to 3 times that of ovum. During the incubation, there is too little dissolved oxygen in the water, and the development of fertilized eggs is hindered, and the number of days of hatching is prolonged. The individual size of hatched larvae is small. The dissolved oxygen in the incubation water should be higher than 6.5 mg/l. 3. Management of fertilized egg hatching Rainbow trout fertilized eggs are swollen and then counted and placed in an incubator for hatching. In addition to horizontal incubators, incubators are now widely used in combination with barrel-type incubators and flat columns. The barrels vary in size, ranging from 20,000 to 100,000 eggs. The water for hatching overflows from the upper part of the lower flow path and then overflows from the upper part. The injection volume per barrel is 4-7 liters/min. The malachite green solution was disinfected every 4 days for 1 hour to inhibit the growth of water mold. Incubation to a cumulative temperature of 220 degrees days, when the eye point is obvious, go into the flat groove to continue. Artificially picked dead eggs during hatching. There are 4 to 6 small tanks flowing from the bottom to the top in the troughs. Each flat column can contain 4 to 60,000 pieces of ophthalmic eggs, and lay the eggs in a flat layer. Adopting the tank and tank combination method to incubate can greatly save water and floor space. The hatchery can be placed in a rack and can hatch nearly 1 million fish eggs in an area of ​​8 barrels per square meter. The flat column is placed on the first floor for easy inspection and management, and it can be kept in the original tank for 2 to 3 weeks after emergence. During the entire incubation period, the eggs were kept quiet and strict light protection measures were adopted. 4. Management of ovum eggs (1) The temperature at which temperature eggs hatch is optimally 9°C, so the temperature should be controlled at 7°C to 13°C. (2) Oxygen causes more oxygen consumption in eye eggs, and even if the water is not used for a short time, it will be too intensive and cause anoxic asphyxia. Therefore, it is necessary to ensure the supply of running water during the incubation period, and be sure to carry water during shipment. (3) Light eggs have very weak resistance to light, and bright light can cause death in a matter of hours. Therefore, appropriate light protection measures should be taken. (4) The vibration should be kept quiet during the entire incubation process to prevent any noise interference and vibrations during handling. Although the resistance of the ovum to the vibration has been relatively enhanced, excessive vibrations should still be prevented. 5. Management of hatched larvae The barrel-type incubator hatches the fertilized eggs to 220 days, and then they are transferred to a flat row for hatching. The amount of eggs to be laid is preferably a tiled floor at the bottom of the tank. The water injection per 10,000 eggs is 8 to 10 liters per minute. Remove dead eggs in time. When the fish eggs in the tank begin to have broken film larvae, inspections should be intensified to clear the egg skins and dead seedlings in time. Attention should be paid to the cleanliness of the breeding environment. Slots are often brushed to keep the water flowing. The newly hatched larvae have a weak physique and a light body color with a yolk sac, lying on the bottom of the trough, and a body length of 15 mm. The yolk sac of the ovary absorbs nutrients and continues to grow. After 16 to 20 days, the yolk sac gradually absorbs. Table melanin increased, swimming ability. At this time, if the slot is not enough for use, the yolk sac can be moved into the juvenile fish pond without direct light, and the vacated horizontal trough can be continuously placed into the irritated ovum of the forthcoming membrane. The rainbow trout at different stages of development is called as follows: hatching up to float, called larvae; up to the bait, called floating juvenile fish; feeding to about 5 months of age (weighing about 10 grams), known as juvenile fish; 5 From the age of the months to the anniversary, it is called the fish of the year; the 1st to 2nd anniversary is called the first-year-old fish. Third, aquaculture technology? (A) the selection and setting of the farm site? 1. The choice of aquaculture sites? Farms are places for rainbow trout farming. In the process of site selection, the purpose of the investigation of natural conditions is to provide a series of good ecological environments for rainbow trout, meet the needs of their normal growth, development, and reproduction at different stages, and at the same time be conducive to production management in order to improve Economic benefits. One of the primary conditions for site selection is the source of water, including the amount of water, changes in annual water temperature, and water quality conditions. • Rainbow trout farming generally adopts high-density water-feeding methods, so the water flow rate limits the scale of the aquaculture water surface. Under normal circumstances, the construction of 600 square meters of cultured water surface, the amount of water per 100 liters to ensure the exchange of water. The rainbow trout's requirement for aquaculture water temperature ranges from 7 to 20°C. Therefore, to understand the indicator of the water temperature measured at the highest and lowest temperatures in a year, the maximum water temperature exceeding 22°C poses a threat to cultured rainbow trout, which is lower than 7°C. It will cause the loss of appetite and slow growth of rainbow trout. The water quality condition is an important content. The quality of water quality is directly related to the success and failure of rainbow trout farming production. • The amount of dissolved oxygen is generally required to be above 6 mg/l. The rainbow trout grows faster at 9 mg/l, and below 4.3 mg/l, the fish gills will be exposed for a long time and will die immediately. If it is less than 3 mg/l, Will die in large numbers. Water should be clear and transparent, rainbow trance likes clear and transparent water, color is generally less than 30 degrees, suspended solids in water should be less than 15 mg/liter. The chemical substances in the water shall comply with the standards of ministerial standards for fishery water use. In the case that the water source and the water environment are already in place, consideration should be given to making full use of the terrain, causing a certain amount of falling water and flow velocity, achieving drainage and irrigation, self-discharging, and reducing water lifting power to reduce production costs. In addition, traffic conditions, power supply, etc. should also be considered together. 2. The farm setup? The farm setup should be based on different natural conditions, economic conditions, and different types of farming. For example, in a comprehensive farm, a full set of facilities should be designed and prepared from broodstock cultivation to food fish cultivation. However, fish farms or fish breeding facilities need not be designed and configured for farms solely engaged in seed production or food fish production. (1) Types and sizes of fish ponds In rainbow trout farming, the types of fish ponds can generally be divided into fry pools, fingerling pools, adult fish ponds, and broodstock ponds depending on the purpose of use. In actual production, it can be used alternately as needed. The size of the fish pond should be determined according to the actual situation in the area. General fry pool area of ​​10 to 30 square meters, water depth of 20 to 40 centimeters; fish pond area of ​​50 to 100 square meters, water depth of 40 to 60 centimeters; adult fish pond area of ​​100 to 200 square meters, water depth of 60 to 80 centimeters; broodstock area 100 to 300 square meters, water depth 80 to 100 cm. The height of the fish pond should be 20-30 cm above the water surface. ? (2) Shape of fish pond Rainbow trout farming ponds have round, hexagonal, rectangular, etc. rectangular ponds are more practical. The ratio of length to width of fish ponds is generally 1:5-8. The general requirement is that the water flow must be unimpeded, there should be no dead ends, the feeding and management should be convenient, and fishing should be easy. ? Fish ponds are generally built into concrete pools for easy cleaning and management, suitable for high-density stocking. In the arrangement of fish ponds, parallel pools are better than serial pools. If the amount of water is sufficient, the topography and terrain permit, all can be used in the form of a parallel pool. However, in order to make full use of the amount of water, fry and fingerling ponds are often used in parallel, and broodstock and adult fish ponds are connected in series. The number of tandems is generally no more than 3. The fish pond should have a water inlet and outlet, and install a fishing net. The bottom of the pool generally has a slope of 1/100, which is convenient for cleaning dirt. (2) Fish fry cultivation The first month of floating fry fry feeding is the most difficult and most technical stage in rainbow trout farming. This stage must first focus on survival, followed by growth. Because the bigger the size of the fry is, the stronger the vitality, and the speed of the fry will directly affect the growth in the future. Therefore, the growth of the floating seedling cannot be ignored. The newly hatched fry is very tender and weak, dark and dark, and the activity is slow. Because the yolk sac supplies nutrients, no feeding is required at this time. When the yolk sac absorbs more than two-thirds of the total, most fry begin to feed on the fly. At this time, it is necessary to feed the nutritious and easily digestible food in time, otherwise it will easily cause death from black shank disease. At the beginning, it can be fed with egg yolks, leeches, silk worms, etc. It can also be fed with liver and fresh fish. The bait can be fed with a fine mesh of 0.4 mm mesh, or it can be applied to a thin wire to hang in the pond for the fish to feed on their own. Feed 6 to 8 times a day, and the daily feed amount is 10% to 12% of the total weight of the fish. After 20 days of feeding, the general body is as long as 2.5 cm and the body weight is 0.2 g. It can be fed to the fingerling pool. (3) Fish breeders The stocking densities of fry and fingerlings vary with fish size, water temperature and water injection. Fry is usually kept under conditions where the water temperature is slightly lower and it is not easy to get sick. The survival rate is high. The average body weight reached 1 gram. It takes about 60 days from the start of eating at a water temperature of 15°C, and about 75 days at a water temperature of 10°C. After 20 to 30 days, the body weight can reach 2 grams. With the growth of fry and the enhancement of swimming ability, the amount of water can be appropriately increased. (D) Adult fish rearing? In order to obtain high breeding efficiency, it is necessary to strive for maximum production volume in terms of limited pond area and water consumption. For this reason, the maximum stocking density and good feed efficiency should always be maintained in all fish ponds so that rainbow trout can grow up healthily. Since the supply of water is mainly the supply of oxygen, and the oxygen is related to the temperature, the amount of water, temperature and oxygen are the three major factors affecting the rearing density. Feed is the key to high-density cultivation. The quality of the feed is critical because the nutrients of the fish under compact conditions are completely dependent on the artificial feed intake. In order to make feed nutrients meet the needs of fish growth, through scientific cooperation, the protein content in the feed will reach the required amount of rainbow trout, so that essential amino acids will be kept in balance, and the nutritional price of protein in feed will be increased. The full-price feed for rainbow trout fish species and adult fish has 40% to 45% crude protein, 6% to 16% crude fat, 2% to 5% crude fiber, and 5% to 13% ash. %, moisture 8% to 12%. The daily feeding amount is generally not more than 3% of the total weight of the fish body, and the daily feeding is 2 to 3 times. The dissolved oxygen status of pool water is an important indicator of water quality control under close nutrition. When the water quantity is sufficient, there is no need to increase oxygen to obtain a considerable amount of production. Normally, the watering rate is best when the water injection rate is 10 to 15. Water injection rate can be obtained by the following formula: Water injection rate (l/s) Water injection rate =——————1000 Feeding fish weight (kg) When the water injection rate is too low, indicating that the water is insufficient for use, it needs to be improved by adding oxygen. Dissolve oxygen in the pool so that the amount of dissolved oxygen in the pool drain is controlled at 5 mg/l or more. Fourth, fish disease prevention and control of fish disease in rainbow trout farming is very important, especially when high-density feeding, more prone to fish disease. Strengthening fish disease prevention and minimizing the losses caused by fish diseases is one of the important measures to improve the survival rate of fish and increase economic efficiency. Inhabiting fish in the water, it is difficult to diagnose and treat its disease. Treating fish disease after treatment can only save the fish that has not been attacked or the disease is lighter. It is also difficult for fish with severe disease to use drugs. Effective. Therefore, the key to controlling fish diseases lies in prevention. According to different pathogens, fish diseases can be roughly divided into infectious fish diseases, invasive fish diseases and other fish diseases. Causes of rainbow trout are mainly caused by biological factors, environmental factors and human factors. (1) Biological factors Rainbow trout is a common disease that is caused by various organisms that infect or invade fish. These organisms that cause rainbow trout are known as pathogens. According to current data, rainbow trout pathogens include viruses, bacteria, fungi, protozoa, worms, and the like. (2) Environmental factors Rainbow trout is a warm-tempered animal. Body temperature changes with changes in external conditions. If the water temperature changes drastically, the fish body cannot adapt, which may lead to the occurrence of various diseases. Rainbow trout has certain requirements for water temperature at different stages of development. Rapid changes in water temperature can cause massive deaths. Aquaculture ponds inflow agricultural water, pesticide water, and industrial wastewater containing heavy metals, which contain various nitrides, can cause excessive organic matter in the pool, deteriorate water quality, and cause poor growth or death of fish. (3) Human factors that are improperly handled during fishing and transportation are likely to cause mechanical damage. After injury, the fish body is vulnerable to infection by bacteria and water mold in the water body. Improper feeding and management can also lead to fish disease. Loss of balance or lack of a certain ingredient in the various nutrients in the feed will cause the rainbow trout to develop a nutritional disease and not grow normally. The resistance will be weakened, and the susceptible bacteria or parasite will invade. (I) Prevention of Fish Diseases 1. Prevention of Infectious Diseases Among rainbow trout diseases, viral fish diseases pose the greatest threat. Such as infectious pancreatic necrosis (IPN), infectious hematopoietic organ necrosis (IHN), viral hemorrhagic septicemia (VHS), etc., these diseases often bring serious harm to the breeding industry. Therefore, it has attracted the attention of various countries and has done a lot of research work. Although various countries have proposed some prevention and control measures, they have been ineffective. For the above three viral diseases, preventive measures are mainly adopted. We must be cautious about importing ophthalmic eggs and strive to purchase breeding grounds free of viral diseases. After the eggs are transported, they must be treated with organic iodine for 15 minutes. 2. The prevention of nutritional diseases The cause of fishes is caused by peroxide poisoning caused by the oxidation of fats in feed ingredients. Therefore, it is necessary not only to pay attention to the diversity of feed ingredient ingredients in order to make a variety of feed ingredients. The nutrition is complementary, and at the same time, we must pay attention to the quality and quantity of the essential fatty acids in the feed, and add antioxidants during the processing. In addition, the shelf life of formulated feeds should not be too long to prevent oxidation of fats and peroxides causing rainbow trout poisoning. (b) Treatment of common diseases 1. Gill disease? Gill disease can be caused by bacteria, but it can also be caused by parasites or molds. Diseased fish are not lively, cover the outside, and swim slowly at the edge of the pool and drain, do not love feeding, excretion of abnormal mucus, and partial fading. In severe cases, the bacteria cover the entire surface of the cockroach and lose its normal function. Water temperature 4 ~ 9 °C when the disease prone to more common in the spring. Control methods: Bath with 2,000 times of copper sulfate solution for 1 to 2 minutes, or add 5 to 10 grams of furazolidone bait for every 50 kg of fish body weight. 2. Arthritis? Caused by bacteria. The sores on the fish's trunk were produced on the local tissue. The lesions were mostly located near the base of the dorsal fins of the fish. The subcutaneous muscles formed infected lesions, necrosis, and ulceration. ? Control methods: According to every 50 kg of fish body weight made with 2.5 grams of sulfathiazole bait, one course of treatment per week, the first day drug doubled. 3. 3. Sphaerothecium? As aquatic fungi are saprophytic, healthy rainbow trout and live eggs are generally not infected. The disease of rainbow trout is mostly caused by the invasion of pathogens after being injured on the body surface. Control methods: immersed in 4% saline for 10 to 15 minutes, or dip for 10 to 6 hours in malachite green solution at a concentration of 10 -6. Incubating fish eggs can be washed with malachite green solution at a concentration of 510 -6 for 1 hour. . 4. Squash disease, also known as white spot disease, is a widespread and dangerous ciliate disease. The small melon worm exfoliates the cytoplasm in the fish's skin and tendon tissue. The host is stimulated to secrete mucus and forms a white vesicle, which presents many large white spots. If left untreated, it will cause a large number of deaths. • Control methods: A malachite green solution with a concentration of 410-6 is dipped for 1 hour or a 1/4000 concentration of formalin solution is dipped for 1 hour. 5. The third generation of worms? Parasites are parasitic on the body surface of fish, and most of them parasitize the axillary and dorsal fins of fish. The maggots of the fish are swollen, the lids of the fish are open, and the silk is dark. The fish is dark and dull, and swims out of the colon. The diseased fish do not ingest and gradually die of thinness. Control methods: use malachite green solution with a concentration of 110-6～210-6 to dip for 30-60 minutes, or dip for 20-30 minutes with 2010-6 concentration of potassium permanganate solution, or use 2% salt solution Dip for 2 minutes.