<h1 class="pgc-h-arrow-right" > preface:</h1>
Rainbow trout is a salmonid, like to jump, after the hook will fight fiercely, originally lived in northern North America and the west coast of the Pacific Ocean, and was later introduced to aquaculture by many countries. Rainbow trout prefer to inhabit lakes and rapids, and its body color is not only bright, but also has small black spots on its body. Because the rainbow trout has a red band on the side of the body, which is shaped like a rainbow, it has the beautiful name of "rainbow trout".
"Ginseng in the water" rainbow trout living conditions are high, the key is to do these steps well, and the pond care produces precious products
<h1 class = "pgc-h-arrow-right" > the understanding of the biological characteristics of rainbow trout</h1>
(1) Life habits
1. Water temperature Rainbow trout is a fish that lives in cold water, and has relatively high requirements for growing water quality, and usually lives in flowing water with clear water quality, gravel substrate and sufficient oxygen. Its living water temperature is generally between 5 and 24 ° C, the suitable water temperature is 7 ~ 18 ° C, and the most suitable growth water temperature is 13 ~ 18 ° C.
Rainbow trout grows rapidly and feeds vigorously within the water temperature conditions suitable for growth, and the body can maintain a good metabolic state. When the temperature of the living water body is lower than 7 ° C or higher than 20 ° C, the feeding of rainbow trout will stop, and the body will slowly fail until death. In natural living waters with abundant water and sufficient dissolved oxygen, rainbow trout can tolerate water temperatures above 24 °C, while under the conditions of artificial farms, the water temperature will be at risk of death at about 22 °C.
2. Water flow rate Rainbow trout has the habit of living with reverse current and oxygen, and under the stimulation of water flow, it can not only accelerate the metabolism of substances in its body, but also take away the excrement in the living waters. Therefore, it should be continuously supplied with fresh and dissolved oxygen water to meet the life needs of rainbow trout for oxygen. 2~3cm/s is the most suitable flow rate for rainbow trout living water bodies.
3. Dissolved oxygen volume The dissolved oxygen content of the water body of rainbow trout is above 5mg/L is a general requirement. To make rainbow trout grow well, the amount of dissolved oxygen in the water is best controlled at more than 6mg/L; when the dissolved oxygen is above 9mg/L, the rainbow trout has a strong appetite and grows rapidly. When the dissolved oxygen of the living water body is less than 5mg/L, the respiratory rate of rainbow trout will be accelerated, and it is difficult to breathe; when it is lower than 4.3mg/L, the rainbow trout lasts for a long time in the water injection department, the top of the fish head is yellow, and the gill cover is open, that is, the rainbow trout "floating head", and death occurs at the same time; when it is lower than 3mg/L, the value is the lethal concentration of the summer rainbow trout, and the rainbow trout will suffocate and cause a large number of deaths.
4. Water Quality Index Rainbow trout likes to live in a clean and transparent water environment. In a complex growth environment, suspended solids in water falling on the gills can cause them to have difficulty breathing and, in severe cases, cause suffocation. Rainbow trout stop feeding in the turbid water, and their growth is blocked, resulting in death. Turbid water bodies have a greater impact on juveniles, and turbid water during heavy rains and floods can increase the number of juvenile and juvenile deaths. In addition to being affected by temperature and oxygen, rainbow trout has certain requirements for the indicators of domestic water quality. Rainbow trout generally live in water bodies with a pH of between 5.5 and 9.2, while the most suitable pH is 6.5 to 6.9. In addition, the adaptability of rainbow trout to salinity will continue to increase with the growth of individuals at different growth stages, and the general juvenile fish can adapt to 0.5% to 0.8% salinity, and the fish of the year can grow in water with 1.2% to 1.4% salinity. Rainbow trout individuals who usually weigh more than 35 g can adapt to life in seawater after transitioning through brackish water.
(2) Eating habits
Rainbow trout is a carnivorous fish that feeds mainly on terrestrial or aquatic insects, crustaceans, shellfish, small fish and shrimp and fish eggs, but also eats the leaves and seeds of aquatic plants. In the juvenile stage, it generally feeds on clades in water bodies, benthic animals such as hairy fins, coleoptera, dragonflies, aquatic insects, and zooplankton. Rainbow trout need to feed all year round, even during the spawning period. Under artificial rearing conditions, artificially fed rainbow trout can also be well fed. The daily feeding intake of rainbow trout is often affected by changes in ecological conditions such as ambient temperature and dissolved oxygen.
The growth of rainbow trout varies greatly depending on the change in water temperature, environmental conditions, and the amount of bait given. Under suitable ecological conditions, rainbow trout can grow all year round. When the water temperature is at 14 ° C, the weight of rainbow trout in one year can usually reach 100 to 200g, the weight of 400 to 1000g for two years, and the weight of 1000 to 2000g for three years. Under the water temperature conditions of 9 °C, the weight of rainbow trout in one year can reach 41 to 51g, the weight of two years can reach 210 to 310g, and the weight of 810 to 1100g can reach three years. In addition, the lifespan of rainbow trout is generally 8 to 11 years.
<h1 class = "pgc-h-arrow-right" > second, farm construction</h1>
The artificial culture of rainbow trout generally adopts the method of high-density flowing water, so the size of the water flow determines the scale of the aquaculture water surface. Under normal circumstances, the construction of 600 square meters of aquaculture water surface, the amount of water injected per second must be at least 100L to ensure the daily exchange of water bodies. Where the perennial water temperature is maintained at 7 ~ 20 ° C, the dissolved oxygen amount is above 5mg/L, the pH is 6.5 ~ 8, and the water quality is fresh, a rainbow trout farm can be built.
Usually, the area of fish fry pond is 10 to 30 square meters, the area of fish fingerling pond is 30 to 50 square meters, and the area of adult fish breeding pond is about 100 square meters. The ratio of length and width is generally 6:1 to 7.5:1. The water flow is smooth, ensuring that the water body does not leave dead corners to fully exchange and renew. Each pond needs to be built inlet, drainage outlet and sewage outlet. The size of the net should be determined according to the size of the fish body of each functional pool, so as not to affect the water flow and not to escape the fish. A certain slope is set at the bottom of the breeding pond, and the inlet should be higher than the aquaculture water surface. The inner wall and bottom of the cement pond can be smoothed with cement to prevent rainbow trout from escaping. The newly built cement breeding pond should be soaked in water for about 30 days and replaced from time to time, and finally need to be disinfected before it can be used.
<h1 class = "pgc-h-arrow-right" > third, adult fish farming</h1>
Where conditions permit, stocking is proportional to production, and stocking can be determined according to fingerling sizes, planned yields, adult fish plans, marketing specifications, survival rates, meat multiples, water source conditions, water temperature, bait and culture techniques. When the fingerling size is 50 to 100g, the stocking amount is 150 to 200 fish/㎡; the fingerling size is 100-150g, and the stocking amount is changed to 100-150 fish/㎡. The water depth of adult culture is 60 to 80 cm, and the daily bait is fed 2 to 3 times a day, and the daily bait rate does not exceed 3%. The diameter of the feed is 4 to 8 mm as well.
<h1 class= "pgc-h-arrow-right" > fourth, feed</h1>
Rainbow trout culture feeding can be combined with pellets, in different stages of breeding, the content of crude protein in the feed and the content of animal protein components in the feed are different.
(1). The content of crude protein in the feed is more than 45% to 50%, and the requirements for animal protein components such as fishmeal are higher, and must not be less than 60%.
(2). The crude protein content in the feed is not less than 40% in the adult fish breeding stage, which can increase the proportion of plant protein in the feed, and the content of animal proteins such as fishmeal is about 40%. It is required that the feed has no mildew and no deterioration, and the size of the feed particles should be determined according to the size of the fish body at each stage of breeding, and it is appropriate to be palatable.
The baiting time is generally arranged around 8:00 in the morning and 5 to 6:00 in the afternoon. When feeding, we should adhere to the "four looks", that is, to see the quality, look at the climate, look at the weather, look at the activities of the fish, and the "four certainties" principle of quality, quantity, timing and positioning, feed on demand, and eat 80% full. Feeding bait by hand should be slow first, then fast and then slow, first in the middle and then on both sides, and the throwing surface of the bait should be large and even.
<h1 class = "pgc-h-arrow-right" > five, common disease prevention and control</h1>
1. Bacterial gill disease
(1). Symptoms The sick fish have no appetite, swim slowly or swim alone, gills bleed in the early stage of the disease, excessive mucus, and swollen gills. In severe cases, the bacterium covers the entire gill surface, and the cap cannot be completely closed. The gills die and fester. Generally, it is easy to occur in the piglet stage, and it is most likely to occur when the weight is about 3g.
(2). Prevention and treatment can be used 1mg/L of furazolidone bath for 1 hour, or 1mg/L malachite green bath for 1 hour; each kilogram of body weight with chloramphenicol or tetracycline 50mg made into medicinal bait, feeding for 5 to 7 days.
2. Infectious pancreatic necrosis (IPN)
(1). Symptoms The sick fish has a black body color, an inflated abdomen, a protruding eyeball, a white fin, a reddish silk, no food in the intestine and full of white mucus, and a gray or congested liver. The fish spun wildly, scurrying up and down, and clotting blood clots appeared in the pylorus. When the water temperature is 13 ~ 15 ° C, it is easy to develop this disease. The disease is divided into acute and chronic, and the introduction of 2-month-old seedlings often causes acute mass deaths. Chronic symptoms mainly affect juvenile fish aged 4 to 8 months, and the onset period can last for two months. When the water temperature is 10 to 12 °C, the mortality rate can be as high as 80% to 100%.
(2). Prevention and treatment At present, there is no symptomatic treatment method, only to strengthen prevention, generally use 1/2000 ~ 1/500 formalin to disinfect fish ponds and production tools, and the use of low temperature rearing when fry are below 5g can effectively reduce the occurrence of viruses. The occurrence of the disease is closely related to the water temperature, below 8 °C and above 15 °C is not easy to occur, therefore, the method of adjusting the water temperature can be used to prevent the occurrence of this disease.
3. Skin mold disease
(1). Symptoms At the beginning of the onset of the disease, white spots appear on the fin end or body surface of the diseased fish, which spread rapidly and form cotton-wool hyphae. Hyphae penetrate deep into the epidermis and enter the muscle tissue, causing muscle ulceration and necrosis. At the same time, the fish secretes a large amount of mucus, showing restlessness.
(2). Prevention and control of salt water bathing: 1% salt water bathing for juvenile fish for 20 minutes; adult fish 2.5% salt water bathing for 10 minutes. 4/10000 salt water and 4/10000 baking soda mixture bath for 1 hour.
4. Granular mucobacterial disease (rotten fin disease)
(1) Symptoms often occur on the dorsal and caudal fins of the densely bred rainbow trout. First, the epithelial hyperplasia of the outer edge of the dorsal fin, caudal fin and ventral fin turns white, gradually expanding to the base, and finally the fin tissue decays and the fin strip is exposed. It is endemic in summer and occurs when the water temperature is above 15 °C.
(2). Prevention and control When the fins are found to be white, it is necessary to immediately adjust the breeding density, increase the amount of water injection, and increase the feeding of inositol and soybean oil and fish oil rich in linolenic acid. It can also be fed with antibiotic bait, rhubarb plus oxytetracycline (2.5 g rhubarb plus 50 mg oxytetracycline per kilogram of fish) mixed with bait for one week. The medicinal bath can be bathed with chloramphenicol 10 mg/L for 30 minutes, or with diarrhea 1 mg/L for 1 hour. To prevent this from occurring, netting should be avoided when the water temperature is high.
5. Vibrio disease
(1). Symptoms This disease is a disease that is extremely harmful to rainbow trout, which is endemic in late spring and autumn, and the water temperature of the disease is above 10 °C. In the early stage of the onset of rainbow trout, the body fin base gradually turns black, the feeding intake decreases, the group swims alone, the eyeball is protruding, and the fin base, anus, and body surface bleeding. In severe cases, the epidermis ruptures, the intestines are congested and lack elastic, the eyeballs are white or bleeding, and the spleen and kidneys are enlarged.
(2). Treatment of oral sulfonamides, the dosage per kilogram of fish body weight is 75 to 100mg, and it is well mixed with feed for one week.
6. Infectious hematopoietic tissue necrosis (IHN)
(1). Symptoms The sick fish has a black body color, swims slowly, expands its abdomen, and drags feces with its anus. The virus initially proliferates in hematopoietic tissue, and then invades the internal organs, causing anemia in the gills, liver, spleen, kidneys, etc., and congestion of muscles and intestines on the side of the body. Bleeding on the surface of the body is a distinctive feature of the disease, especially on the fins of smaller calves. Most of the baby fish harmed by the virus are 0.2 to 0.6 g, and the mortality rate can be as high as 50% to 80%.
(2). Prevention and control The appropriate temperature for virus reproduction is 8 ~ 10 ° C, and reproduction is stopped when it is above 15 ° C, so the disease fish in the early stage of the disease can be put into water with a water temperature of about 18 ° C for 4 to 6 days to prevent and control the disease. The eggs can be isolated and reared after 50mg/L of organic iodine disinfection for 15 minutes to avoid viral infection, and can also be bathed in 2% salt water for 5 to 10 minutes for 2 to 3 consecutive times.
7. Ulcerated cutaneous necrosis (UDN)
(1). Symptoms The damage is limited to the skin, and there are many small gray areas on the head, followed by epidermal shedding, and later mold invasion, which is complicated by water mold.
(2). Prevention and treatment Of this disease is easy to occur when the water temperature is lower than 10 ° C, comprehensive prevention and control measures should be strengthened, multivitamins and vitamin C should be fed, and 3mg/kg chlorine bait should be fed in the early stage of the disease. Sprinkle 0.5 mg/L malachite green solution to prevent complicated water mold disease.
8. Small melon worm disease
(1). Symptoms The disease mainly harms juvenile fish, and small white dotted cysts can be seen on the surface of the sick fish and the gill flap.
(2). Prevention and control 1/4000 formalin bath for 40 minutes, 2 days 1 time, 3 times continuously.
9. Three generations of insect diseases
(1). Symptoms Three generations of insects mainly parasitize on the body surface and gills, damaging the epidermis and gill tissue, making the fish extremely uncomfortable. When fish species and adults parasitize three generations of insects, there is a layer of gray and white mucus on the surface of the body, loss of appetite, and difficulty breathing.
(2). Prevention and control can be soaked with 20mg/L. potassium permanganate solution for 20 to 30 minutes or soaked with 1% ammonia.
10. Slimy bulbous worm disease (madness disease, rotation disease)
(1). Symptoms The disease usually occurs after the fish body is injured. When passing acutely, the sick fish swim in a circle or struggle vertically, and some swim sideways to the side of the ice and spin, losing the ability to feed and dying. During the chronic passage, the sick fish swim in waves, physical fatigue, loss of appetite, and emaciation.
(2). Prevention and control Of the baby fish during the feeding period of a few weeks to 4 months is very susceptible to infection, because the myxosporidium has a thick shell, it is more difficult to treat with drugs. Therefore, in terms of management, it should be done: the discovery of diseased fish, dead fish fish in time, sick fish can not be thrown near the fish pond, to be burned or buried deeply and other pollution-free treatment.
11. Nutritional hepatic steatosis
(1). Causes Continuous feeding of fat oxidation feed, the use of inferior fish meal, mildew and clumped feed, lack of vitamins or incomplete vitamins in the feed, the sugar content in the feed is too high.
(2). Symptoms The feed coefficient increases, the growth of the sick fish is slow, the appetite is low, the body color is blackened, and the color of the silk is lightened; the liver is earthy yellow or light brown, with blood spots; the gallbladder is large, yellow, translucent; the intestine is congested, ulcerated, and there is yellow mucus.
(3). Prevention and control Improve feed quality, increase the feeding of multivitamins, especially vitamin E and choline, and conditionally increase the liver of fresh animals.
<h1 class = "pgc-h-arrow-right" > integrated control measures for rainbow trout disease</h1>
(1). Fry should select excellent varieties with large individuals, strong physique and strong disease resistance.
(2). Improve the amount of dissolved oxygen in the pond water, keep the water body clean and sanitary Especially in the summer, it is necessary to increase the amount of dissolved oxygen in the water body in a timely manner to prevent the floating head of the fish fingerlings.
(3). Daily feeding of fresh, palatable full-price with pellets It is strictly forbidden to use low-quality and mildew feed.
(4). Adhere to the disinfection and sterilization work before the fish body enters the pond During the sick season or regular disinfection of the water body, eliminate the pathogens in the residual water body, and timely feed the medicinal bait for prevention.
(5). Strengthen daily inspections to find timely diagnosis and treatment of diseases, and isolate and raise sick fish. If the nutritional disease can start from improving daily feeding, it can be fed a high-quality, palatable, fresh and nutritious feed.
(6). Prevention with traditional Chinese medicine An appropriate amount of rhubarb powder can be added to the daily feeding, which can effectively prevent the occurrence of parasites and bacterial diseases.