Culture technology of turbot fish

Also known as southern flounder, Atlantic flounder, American flounder, Paralichthys olivaceae, flounder, flounder,

The shape of the turbot is similar to that of Paralichthys olivaceus in China. the side of the body is flat and oval, both eyes are located on the left side of the head, the left side of the body is light brown, with irregular spots, and the belly color is lighter, which can change with the surrounding environment in order to hide the body and avoid enemy attacks. Turbot is a widely salty fish and can usually survive in sea water and fresh water. Females grow faster than males and can reach sexual maturity at two ages. Males usually have a life span of two years, and it is reported that the longest-lived males in South Carolina can reach more than three years. In the case of the same age, the body importance of female fish is significantly greater than that of male fish, and a three-year-old female adult fish can reach about 25 cm. In the natural sea area, the maximum adult fish can grow to 75 cm, and the growth rate of female fish is faster than that of male fish. When the two-year-old fish reach sexual maturity, the length of male fish can reach 20 cm ~ 25.5 cm, and the length of female fish can reach 30 cm ~ 35.6 cm. If the artificial culture is carried out, the growth period will be shortened obviously, the effect will be faster and the benefit will be better. In natural waters, turbot fish have the ability to ambush and prey. The larvae mainly take crustaceans as bait, and gradually feed on all kinds of fish as they grow up, usually preying on spotted mullets, striped mullets, white mullets and prawns.

Turbot is recognized as an excellent farmed fish with the characteristics of fast growth, excellent quality, wide adaptability, strong stress resistance, delicate meat and rich nutrition. Since the early 1990s, the United States began to study the breeding and culture technology of turbot, and has made breakthroughs in physiology, ecology, artificial reproduction and culture technology. Turbot culture has become a rapidly developing new culture industry in the United States. After being introduced into China, this variety is of great development value and has broad development prospects.

Culture of turbot fish

1. The selection of seedling and seedling.

The main results are as follows: (1) specifications: the culture technology of turbot is similar to that of Paralichthys olivaceus, and it is easy to master in production. Generally, when the seedlings grow to more than 5 cm, they can enter the big pond for stocking. It is best to release the seedlings above 8 cm, when the physique of the seedlings is enhanced, the disease resistance is improved, and the adaptability of the fry after entering the pond is strong, and it is easy to improve the survival rate.

(2) Seedling selection: when selecting and purchasing seedlings, pay attention to the fry with complete body shape, normal body color, no deformity, no albinism, no damage to the fin, fast swimming, symmetrical size, no morbid condition, and no Gill parasites.

(3) Seedling release time: outdoor culture, when the water temperature is above 18 ℃, it is suitable to release seedlings from April to May every year. Because the water temperature is too early and the water temperature is low, it is difficult for the fry to adapt, and even reduce the survival rate of the fry; too late will affect its growth into commercial fish that year.

(4) stocking density: pond culture, 500 ~ 800 fish per mu; pond cage culture, 100 ~ 200 fish per 3 m × 3 m × 1.5 m cage; sea area cage culture, 300 ~ 400 fish per 3 m × 3 m × 3.5 m cage; factory greenhouse culture, about 20 fish per square meter.

2. The choice of pond

The existing shrimp ponds can be cultured with a little modification, which requires a water depth of about 1.5 meters, sufficient water source, fresh water quality and good drainage facilities. The bottom of the pond must be treated before releasing seedlings, the silt of the dry pool should be cleared, the bottom of the pond should be loosened, and the weathering and exposure should be carried out for more than 10 days. The influent water is 30 cm ~ 50 cm and is disinfected with bleach. The available chlorine content in the pool water is more than 10ppm, and the bleach containing 25% and 30% chlorine is generally applied to more than 40 grams per cubic meter of water.

Nurturance management

1. Water quality and water exchange

The quality of aquaculture water is related to the success or failure of aquaculture. In the whole process of breeding, we should pay attention to carefully observe the changes of water temperature and water quality, and regularly measure water temperature, dissolved oxygen, salinity, pH value, ammonia nitrogen, sulfide concentration and so on. The regulation of water used for pond culture can be controlled by adjusting the amount of water exchanged. The amount of water exchanged is proportional to the temperature of the water.

2. nutrition and processing of bait

Turbot is a carnivorous benthic fish. Stir vitamins and flour evenly, then mix with fish meal and yeast powder, then add fish oil, add fresh mixed fish and shrimp (or frozen fish and shrimp crushed), put the above mixture into the granulator to make pellet feed. The main raw materials for processing wet pellet feed are Spanish mackerel, sardines, mackerel, noodle fish, green scale fish and other miscellaneous fish, which require good freshness, poor freshness or long freezing time. In the process of breeding, vitamin C, vitamin E and multivitamins can be added to the feed to strengthen the nutrition of fish and prevent disease due to lack of nutrition. Note that the processed bait should be fed on the same day, and the rest should be properly frozen and stored. The maximum storage time should not exceed 2 days to prevent deterioration.

Commercial baits that meet nutritional requirements can be used. Note that when the water temperature is low or high, the feeding times and amount can be reduced appropriately. In principle, there can be no residual bait, and no bait can be taken before the medicine bath.

Prevention and treatment of turbot fish disease

1. Find out the cause of fish disease

(1) the change of water temperature: fish belong to variable temperature animals and can not regulate their body temperature. The body temperature of fish changes with the rise and fall of the water temperature of the living environment. The sudden change of water temperature will cause fish death. Generally, when the temperature of larvae and juveniles is more than 2 ℃ and that of adults is more than 5 ℃, the fish is in a state of stress and is most likely to die at this time.

(2) the content of dissolved oxygen in water: the oxygen consumption of fish is higher. The dissolved oxygen content of fish living environment is often not enough, especially in the case of high-density culture, hypoxia often occurs, and fish are easy to get sick. Therefore, it is very important to take some measures to increase oxygen according to the actual situation. The suitable dissolved oxygen is generally 4 mg / L ~ 12 mg / L, and the most suitable is 8 mg / L ~ 9 mg / L.

(3) COD: less than 3 mg / L. If the content of ammonia nitrogen and COD in the water is too high, the water quality is corrupt and diseases are easy to occur.

(4) pH: the suitable range is 6.0 to 9.5, and the best is between 7 and 8.2. In the process of breeding, as long as you pay attention to regular observation and testing, it is relatively easy to master.

(5) salinity and temperature: strong adaptability to the environment, which is the obvious advantage of turbot compared with other fish. Its suitable salt range is 0: 60, the best is 5: 35, and it can even grow in fresh water. The survival range of water temperature is 1 ℃ ~ 35 ℃, and the suitable range of culture is 18 ℃ ~ 30 ℃.

(6) bait: fish also often "get sick from the mouth", so what kind of bait to choose is very important. In the preparation of fresh bait and compound bait, we should not only pay attention to the matching of nutrition and freshness, but also avoid pollution in the process of processing. Feed protein requirements 32% 48%, the best 38% 48%. Culture for 8 months to 12 months can generally reach about 600 grams ~ 800 grams.

2. Preventive measures of fish disease

The main results are as follows: (1) stocking density: the stocking density of fish fry should be suitable, and the stocking density is too large, resulting in the increase of feeding amount and fish excrement, the decrease of dissolved oxygen and the deterioration of water quality.

(2) Water exchange and decontamination: with the growth of fish fry, it is necessary to gradually increase the amount of water exchange, generally changing water once at the age of 5-10 days, 30%-50%; 2 times at the age of 11-20 days, 40%-60%; and 2 times at the age of 20-30 days, 50%-70%. Once every 1 ~ 2 days, the pond should be desilted at the bottom every year, and the indoor cement pool should absorb the bottom in time to remove impurities.

(3) Filtration and purification: the water for culture in the greenhouse should be purified by sand filtration at least. The fine sand size of sand filter is 0.15 mm ~ 0.25 mm and the thickness is about 60 cm.

(4) strengthen the feeding management: during the culture period, the nutritional requirements of larvae, juveniles and adults must be met, and the food freshness should be good and the nutrition should be complete. Multivitamins, vitamin E, vitamin C and minerals can be added if necessary. The biological bait for breeding must be washed with fresh sea water before feeding, and when there are miscellaneous bacteria, it must be disinfected with antibiotics. The daily feeding times are determined according to the needs of the fish. Feed should be fixed in quality, quantity, timing and positioning. In principle, there can be no residual bait.

(5) Drug prevention and treatment

① fish body disinfection: purchased fish fry, no matter whether there is disease or injury, should be bathed with medicine; the fry breeding stage should be sorted, and medicine bath should also be carried out after pouring into the pond. Commonly used disinfection drugs are formalin, copper sulfate, ferrous sulfate and so on. Formalin at the concentration of 1 × 10 ~ 4 × 10 ~ 2 × 10 ~ 4 can prevent bacterial and parasitic diseases for 60 ~ 120 minutes, and copper sulfate 5 × 10 ~ 7 × 10 ~ 7 and ferrous sulfate 2 × 10 ~ 7 × 10 ~ 3 × 10 ~ 7 can prevent ciliates. In the prevention and treatment of Duobao fish, the use of potassium permanganate is strictly prohibited, because the respiratory system of Japanese flounder is very sensitive to potassium permanganate, and there have been many cases of death of Japanese flounder caused by the application of potassium permanganate.

② pond disinfection: regular water disinfection, the most commonly used is to sprinkle quicklime, 1 mu deep pond dosage of 10 mg ~ 20 mg, can play a role in sterilization and improvement of water quality. In addition, it can also be sterilized with bleach with a concentration of 5 × 10-7.

Estimation of aquaculture benefit (calculated at 200 yuan / kg)

1. Pond culture: 500 to 800 fish can be released per mu, with a survival rate of 80%. After 6 months to 12 months, the average value is 0.5kg / tail ~ 0.8kg / tail, and the income per mu is 60,000 ~ 100000 yuan.

2. Pond cage culture: each 3m × 3m × 1.5m cage is stocked with a survival rate of 80%, reaching an average of 0.5kg / tail ~ 0.7kg / tail after 6 months to 12 months, with an income of 8000 to 20,000 yuan.

3. Cage culture in the sea area: 300 to 400 cages of 3 meters × 3 meters × 3.5 meters are released, with a survival rate of 80%. The average value of 0.5 kg / tail ~ 0.7 kg / tail is reached after 6 months to 12 months, with an income of 20,000 yuan to 40,000 yuan.

4. Industrial greenhouse culture: 20 animals per square meter, with a survival rate of 80%. It reaches 0.5kg / tail ~ 0.8kg / tail after 6 months to 12 months, and the income is 1600 yuan / square meter ~ 2500 yuan / square meter.