Turbot culture technology

First, the biological characteristics of turbot The turbot is a butterfly-shaped head, Aphididae, and Amaranthus. It is naturally distributed on the European coast on the east side of the Atlantic Ocean. It is distributed from the northern part of the Nordic region to the north of North Africa. The Black Sea and the Mediterranean are also distributed. The main distribution is on the North Sea and on the west coast of the Black Sea. The total annual catch on the coasts of Europe and West Asia does not exceed 10,000 tons. The turbot body is flat and round, with eyes on the left side of the body, brown on the side of the eye, a little melanin and a small amount of prickles, no smooth white side of the eye, no hard spines on the dorsal fins and buttocks, and small head and caudal fins The body is thick in the middle, and the visceral mass is small. The whole body has more edible parts than gums. Turbot maximum lethal temperature 28°C-30°C, lowest lethal temperature 1°C-2°C, maximum growth temperature 21°C-22°C, bottom growth temperature 7°C-8°C, optimal growth temperature 14°C- 17°C. The optimum salinity for turbot culture is between 20 ‰-32 , and 25 ‰-30 ‰. The most suitable for salinity is 40 ‰ and the minimum is 12 ‰. Turbot as a benthic fish, swimming usually less, when the bait leaps prey, a docile personality, mutual residual food is rare. During the juvenile period, it only takes about one week from predation of live bait to feed. When feeding with an automatic feeder, turbot is easily domesticated into rhythmic feeding. The bait conversion rate is quite high. Under the conditions of artificial breeding, the stocking density can reach more than 40 kg/?, as long as the head and the head are exposed, the other parts overlap each other by more than 60%, basically no effect on the growth. Turbot aquaculture requires that the water quality is non-polluting. The underground seawater can be pumped directly into the aquaculture pond, and the seawater must be filtered and sterilized. Through the breeding experience of turbot, it is better to use stream culture. The amount of water changed every day is at least 5 or more, and if the amount of water is sufficient, it can be doubled. Turbot grows quickly. According to the breeding experience, it is normally calculated from the seedling length of 5 cm seedlings into the aquaculture pond. 7 months, that is, more than 200 days can grow to about 500 g per tail, reaching the commodity specification. Second, the rearing of male turbot of turbot reaches sexual maturity and the female reaches sexual maturity at the second instar. The natural maturity period is from May to August each year. For artificially cultivated broodstock, mature eggs can be obtained from January to October, under artificially controlled light conditions. At present, artificial breeding still uses artificial insemination. In 1972, the artificial nursery of turbot has been successful, and it has only reached the level of small-scale production so far, indicating that artificial breeding of turbot is difficult. In Britain, the survival rate from incubation to metamorphosis is only 1%-25%. The average is only 3%-6%. The fertilized eggs hatch in still water and can also be hatched with running water. The incubation temperature is 12°C-15°C. The newly hatched larvae are cultured in circular glass steel tanks or concrete tanks with a volume of 10-20 cubic meters. The cultivation density is 5-20 tails/liter, and the light is continuously irradiated for about 14 hours per day. The surface illumination of the water is 200-1000 lux. Inflated, the water temperature gradually increased, and finally increased to 20 °C. The larvae began feeding on the third day after hatching and were bred twice a day with a rotifer density of 5-10 cells/ml. During the first ten days, some of the unicellular algae were added (preferably adding Phaeodactylum tricornutum and Isochrysis) to act as bait for rotifers. The larvae were fed Artemia nauplii 6-10 days after hatching, and Artemia nauplii was cast for 20-25 days. When larvae reach 20 mm in length, they can be fed with artificial diets. Promotes fish to switch foods, gradually thinning preference for live baits. The survival rate of turbot after conversion of food was 85%. The eyes of the larvae move to the side to complete metamorphosis, which takes about 70 days. The total length is about 30 mm. Generally, the survival rate of artificial rearing of turbot is calculated at this time. After 80 days of metamorphic juveniles have been completed, they can be transferred to larger ponds for 20-30?, all of which are fed to the workers' compound feed. At this time, the lighting, flowing water and aeration measures are the same as before. Third, the turbot breeding process 1, the construction of plastic greenhouses (1) Rich and abundant underground water is the prerequisite for the construction of greenhouses, for aquaculture. Groundwater temperature is stable and the water quality is good. It can save energy, reduce consumption, and accelerate growth for industrial fish farming. Greenhouses must be constructed where they can produce seawater wells. Wells have sufficient water and water temperature, and the water quality meets the fishery water quality standards and is relatively stable. From the current experience, the well depth is 13-120 meters, and the annual water temperature can be controlled at about 13-18 DEG C; the well depth is 80-120 meters, and the water temperature can be maintained at the level of 11-15 DEG C., which is very high for the cultured turbot. ideal. In order to ensure that the amount of water is easy to replenish and avoid the occurrence of draining, the seawater well is best played in the intertidal zone near the high tide line. Because of the different geological structures in different areas, the underground aquifers are very different, and the salinity and chemical composition of the underground wells vary greatly. Therefore, the well water that is produced cannot be treated with clean water as the standard. It is necessary to ask professional institutions and departments to carry out geological exploration and water quality testing. After the fish test is ensured to be correct, the address can be determined to build a greenhouse and pump fish. (2) The structure of greenhouses for fish farming is similar to that of warm winter vegetable greenhouses. The walls are made of red brick cement, steel simple arched roof trusses, double-layered fishing shed plastic film for roofing, a layer of straw curtains on the roof, and the top of the straw curtain is covered with a layer of large buckle fishing nets to tighten and buckle on the roof. Around the pegs to prevent the straw curtain from being blown away. Aquarium tank bottom reinforced concrete pouring, surface waterproofing using five-layer treatment, slope down 5%. The wall of the pool is made of red brick cement mortar. The inner wall of the pool is treated with five layers of waterproofing. The outer wall of the pool is plastered with cement mortar. The bottom of the pool is pre-embedded with drainage pipes. The drain outlet is at the bottom of the pool. The drain overflow pipe is inserted vertically into the elbow of the drainage well outside the pool and can be inserted and removed at any time. There are two kinds of round-shaped and square-shaped pools, and square-shaped aquariums are rounded in four corners so that the pool water can circulate. There are 5*5, 6*6, 7*7 and other specifications in the pool. The depth of the pool is 60-80 cm. There are 6-10 diffusing stones per pool, two inlet pipes, and a tangential line with the upper mouth of the pool. Each greenhouse building 700-1000?, two rows of rearing ponds with a main water inlet pipe and drainage ditch, the main water inlet pipe leads to the well water, through the various fish ponds. Greenhouses can be built separately, or several can be built together, and can be built together with living areas, very flexible and convenient. (3) In addition to temperature advantage of underground seawater, all other indicators are lower than natural seawater. The dissolved oxygen is low, and the content of harmful substances such as ammonia nitrogen, carbon dioxide, hydrogen sulfide, and heavy metal ions is high. If it is not treated, turbot lives in such a water environment for a long time. The accumulation of harmful substances will cause chronic poisoning, resulting in slow growth, physical weakness, reduced survival rate and easy outbreak of fish disease, affecting economic efficiency. Therefore, underground seawater must be treated with aeration before entering the fish pond. The role of the waterfall is to increase dissolved oxygen in the water, balance the total gas level of the water, and remove harmful substances such as harmful gases, organic matter, and heavy metal ions. 2. Breeding process (1) The quality of the purchase and transportation of seedlings determines the growth and survival rate of turbot, directly affecting the economic benefits of farmers. Should choose a healthy body, swimming and lively, the specifications are neat, the size is appropriate, normal body shape without deformity, there is no damage to fish and parasites without high-quality fry. Normal body color, back with sand color, smooth body surface, transparent dorsal fins and anal fins, body elasticity, concentrated life at the bottom of the pool, and stimulating or frightened when the swimmer's seed is the best. As far as possible, the nursery farms are selected to breed larger-sized seedlings of the same batch of seedlings. Smaller seedlings grow slowly in the breeding process, and it is easy to become an "old fish" without aquaculture value, resulting in waste of cost. In addition, the hatching rate and the low survival seedlings and the last seedlings during the seedling breeding process are best not to be purchased. Judging from the existing experience in production and breeding, large-size seedlings have strong adaptability to the environment, high survival rate, and low disease risk. Therefore, large-scale seedlings should be selected as far as possible to ensure the seedlings that enter the pool. Specifications are at least 5cm and seed sizes up to 8-10cm are better. The turbot seedlings are transported in a plastic bag filled with oxygen and sealed. The fry is stopped for 12-24 hours before transport. The temperature of the water to be transported depends on the season and time. It is generally required that the temperature difference between the water temperature in the two places of transport should not exceed 2°C. The process of packing and transporting first adds 1/5-2/5 sand-filtered seawater to the plastic bag, then counts, puts the seedlings, discharges the air in the bag, fills in pure oxygen, seals, and encapsulates it into the foam box. In order to prevent the water temperature during transportation from increasing, appropriate amount of ice cubes can be added to the foam box to cool down. For seedlings of 5-7cm in size, 150-200 tails can be placed in each bag; for 8-10 cm seedlings, 100-150 tails can be loaded in each bag. When transporting long distances, it is necessary to reduce the bumpiness of the vehicle as much as possible. In order to improve the survival rate of transportation, it is best to add antibacterial drugs such as nitrofurazone or oxytetracycline to the plastic bag to prevent the fish from colliding with each other and causing friction and injury, resulting in bacterial infection. When you arrive at the destination, unpack and unpack it, try the temperature difference and salinity first. After the fry is in the pool, use 15-25ppm oxytetracycline or nitrofurazone for continuous bathing for 3-5 days, 1-2 times a day for 1-2 hours. At the same time can be fed a dose of 100-150mg oxytetracycline / kg / day, can also be added to the bait herbs or nutritional additives, increase the immunity of fry, improve the disease resistance of fry (2) seed stocking and sorting seedlings The stocking density is closely related to feeding conditions, water quality, water exchange capacity, management level, and personnel quality. It should be based on the principles of water saving, energy saving, and convenient management. It is usually expressed in terms of the body weight or the number of tails of fry released per unit area. In the greenhouse cultivation conditions, 6-10cm seed can be 80-150 tail /?, adult fish breeding density of about 20-30 tail /?. Turbot is a fast-growing fish with a growth rate of up to one kilogram in the first year and a growth rate of more than one kilogram in the second and third years. Although there is no phenomenon of residual food between turbot, but in the same aquaculture water, due to the palatability of the feed, the feeding capacity of the fry, the social hierarchy, and other reasons, the growth of the seed is fast and slow. After a period of cultivation, There is a wide disparity in individual sizes. Small individual fish fry are more difficult to catch food and grow slowly. If they grow for a long time, they form “old fish”. Attention should be paid to separation to promote the growth of small individual fry and increase the survival rate. Note that the separation can not cause anoxic conditions. After the water level of the tank is reduced, the amount of aeration should be increased, and the sorting should be performed while the water is flowing. The best sorting of a pool is completed once. To prevent the disease, the sorted fish fry were treated with 15-25 ppm oxytetracycline hydrochloride or nitrofurazone once a day for one hour for three consecutive days. (3) Feed Processing and Feeding a. Feed processing feed ingredients must be fresh. Jade fish, sardines, horse mackerel, squid, and other sea catching of miscellaneous fish are the main raw materials for making turbot feed. Fresh fish generally account for 50% or slightly higher feed. The fresh fish must be fresh and can be processed after washing. Never use miscellaneous and odorless fish. When buying fish, it's best not to have a single variety, but to purchase small fish that are small enough to be adult fish. Avoid long-term use of carp for feed, because small carp has low nutritional value and high water content. The long-term consumption of small squid feed by turbot causes malnutrition and slow growth. Turbot is a cold-water benthic living fish with less activity, high protein demand, and relatively low demand for carbohydrates. The protein contained in the feed is consumed as energy in addition to the fish protein. If too many carbohydrates are fed, turbot cannot be digested to become pathological. The common cakes, quail feeds and other low-value feed sources contain anti-nutritional factors. Without detoxification, there are adverse effects on the growth and health of aquatic animals. Therefore, raw materials such as bean cake, wheat bran, and black noodles must not be incorporated into the feed. In order to promote the increase of turbot plumage, it is best to add 3-5% of refined fish oil. According to the current successful farming experience, it is suggested that the feed formulation of turbot is as simple as possible. Usually 50-60% of fresh fish is fished into fish paste, and 40-50% of “Hanye” brand turbot special powder feed is used. According to different stages, add 3-5% of fish oil and use a bait machine to squeeze and mix. In production, we must pay great attention to the raw materials, processing equipment, and site sanitation inspection management. We will strengthen the disinfection of raw materials, especially fresh fish, and strive to improve the hygiene standards for the entire process of feed processing. All kinds of raw materials must be fully mixed, especially drugs and additives must be first stirred in the powder even to prevent excessive amounts of additives in the particles cause fish poisoning, self-made feed should be used as far as possible with the current allocation, to avoid making a single feed for multiple shots Hey. After the feed is prepared, it is really necessary to freeze and store it in small capacity. The size of feed pellets must change with growth. The machinery, tools, and containers used to make the feed must be promptly cleaned after use, ventilated and air-dried to prepare for the next use. b. Feeding the fish 100g before the daily feeding frequency 6-4 times, and weighing 150g after the daily feeding frequency 3-2 times. When the water temperature is lower than 12°C or higher than 22°C, when the fish eats food poorly, the number of feedings and the amount of feeding and even the bait may be appropriately reduced, and it is particularly noticeable that no bait can be given before the medicinal bath. The amount of daily feeding is 6% of the weight of the fish. The specific amount of bait is determined based on the fish's feeding condition. In principle, there can be no residual bait. When feeding, attention should be paid to observe the fish's feeding conditions and changes in food intake. If poor food intake is found, identify the cause in a timely manner and pay attention to the analysis of water quality problems and the signs of fish diseases. To promote the use of dedicated dry pellet feeds compared to wet feeds, the use of dry compound feed for turbot has more comprehensive nutrition and lighter water pollution, which will help reduce the occurrence of diseases. The "Hanye" brand turbot dedicated dry pellet feed not only considers the issue of promoting growth and increasing the conversion rate, but also considers the effects of immune defense, the impact on the environment and fish quality, etc., and is more in line with the physiological needs of fish. To maximize the use of protein for growth, with sufficient fat to meet the fish's energy needs for growth. In order to effectively solve the various problems existing in the farm feed in homemade feed, the true meaning of industrialized fish farming is reflected. (4) In addition to the determination of the water temperature during the water quality management and cultivation, there are fish farms with laboratory conditions. It is best to test the dissolved oxygen, salinity, pH value, sulfide content, and ammonia nitrogen concentration of the water every day. The adjustment of water quality is mainly controlled by adjusting the amount of water exchanged. The water exchange volume shall be maintained at 5-10 cycles/day, and comprehensive consideration shall be given based on the cultivation density and water supply conditions. When the water temperature is 20°C, the water exchange volume should be increased in principle. When the water temperature is above 22°C for a long time, it is necessary to take cooling measures. In order to prevent the occurrence of hyperthermia reaction of turbot causing congestive death. After each feeding is completed, the sewage pipe should be removed, the water gate should be quickly lowered, and the pool water should be quickly rotated. The water quality in the pool should be completely improved, and a large amount of dirt and bait should be removed from the bottom of the pool. At the same time to clean the pool wall and inflatable tube, sticky dirt on the gas stone. In addition, remove dead fish, concentrate it, or burn it with fire. Buckets, fishing nets, etc. are disinfected with disinfectants.

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