A farmer friend called and consulted on the aquaculture technology and disease prevention and control of the clamp fish. The author interviewed Yang Zhuangzhi, head of the Chengdu Aquatic Technology Promotion Station.
According to Yang Zhuangzhi, the pincers are spotted on the tail (also known as the gully), which has the characteristics of complex feeding, disease resistance, wide adaptability, rapid growth, tender meat, rich nutrition, and high economic value. Forktails like to live in dark conditions, temperature range of 0-38 degrees, 5 degrees to start feeding, suitable for growth temperature 18-30 degrees, p H 6-8.5, dissolved oxygen 3 mg / liter or more. It grows rapidly under pond culture conditions. It usually grows to 14-20 cm body length and 30-100 g body weight in the first year; it can grow to body length 40-55 cm and weight 800-1500 g in the second year. The body length is 5-6 cm before it is larvae, mainly feeding on zooplankton, such as rotifers, cladocera, copepods and so on. From 10 cm to 10 days of body length, they mainly feed on organic debris such as benthic organisms, aquatic insects, terrestrial insects, and animal foods; under artificial breeding conditions, they mainly feed on compound feeds.
The catfish can be cultured in ponds and stocked on large surfaces such as reservoirs. It is also an important species for high-density flow culture, cage culture, and factory culture. At present, the adult culture methods of spotted fork tails mainly include pond breeding and cage culture.
Pond culture
First, fish species stocking
The pond area requires more than 3 acres, water depth is 1.5 meters or more, sufficient water supply, convenient drainage and drainage, no pollution, and 1 aerator every 10 mu. Before the fish species are stocked, they shall be disinfected with clear lime and bleaching powder. The farming methods can be divided into two types: pond single-cultivation and pond polyculture.
The speckled fish rearing stock size is 15-20 cm, and other species stocking specifications are 30-50 g each. The stocking time of the fish species is generally from December to February of the following year, or the fish of the channelling fish is directly transferred from a large-scale fish breeding pond into a fish pond for breeding in autumn.
Second, day-to-day management adheres to the tour pond. Every day, morning, evening, and night, stick to the pond and observe the fish's feeding and activities.
Scientific training. Every time before going out of the pond for handling or sieving, training must be conducted, otherwise it is easy to cause a large number of deaths due to injuries. The training method is the same as that of the home fish. The first time the net box was pulled, no operation was performed and it was returned to the original pond in the afternoon. The next morning and then pull the online box, you can sifted or carried in the afternoon. After the end of the operation, soak in 2%-3% saline for 5-10 minutes and splash lime with lime or bleach for 2-3 days once a day.
Adjust p H . Every half month, 50-100 mg/L lime slurry is sprayed once to adjust the p H of the water to slightly alkaline to inhibit the growth of harmful bacteria in the water body.
Control water level. In early spring, the temperature rises quickly, and the pond water level should be shallow, controlled at 0.8-1 meter. Cold winter weather, fish frostbite pond water level should be added to the highest place.
Add new water. During the high temperature season, the fish has a large amount of activity, strong metabolism, and rapid changes in water quality. It is necessary to frequently add new water, and water can be added once every 3-5 days. Each water addition depends on the water body, water, and water quality. Generally, water is added at each time. -35 cm. Maintain a transparency of 20-25 cm.
Timing oxygenation. Through the flow of the upper and lower water layers, it promotes the exchange and mixing of water bodies, increases the dissolved oxygen in the bottom layer, and decomposes and emits toxic gases; it repays the oxygen debts in advance. The use of aerators is generally open at noon on sunny days and open early in the morning on cloudy days. Rainy weather or water and fertilizers need to be prevented from opening in the middle of the day.
prevent disease. In the epidemic season of fish disease, we must prevent it in advance. The combination of extravasation and oral administration can effectively prevent the occurrence of diseases. Commonly used in vitro spilled drugs are lime, bleach, strong chlorine, etc.; oral drugs are oxytetracycline, furazolidone and so on.
Cage culture
I. Water area selection and cage structure
Water area selection. Requires convenient transportation, wide water surface, sheltered from the sun, quiet environment, no pollution, micro-flowing water, transparency greater than 1 meter, water depth 4 meters above, p H 6.5-8, dissolved oxygen above 5 mg/l, cage area and water area ratio Greater than 1:300.
Cage structure. The cages are arranged in a "non-" shape. The cages are assembled into 1 row per acre. The distance between the rows is more than 100 meters. To adapt to the change of water level, the floating cages are better. The cage size is 3 meters and 4 meters and 2.5 meters. Open type pentahedral cages.
Large-scale species breeding. Before the fish are put into the box, the new cages to be placed and placed in the water will be soaked in water for 7-10 days to attach attachments and reduce the scratches on the fish. The fish will be fed as soon as possible after entering the box, and the fish will be fed as soon as possible. The full price with pellet feed. At the beginning, a round-shaped bait station with a diameter of 1 meter was hung in the center of the box at a distance of 50 cm from the water surface. The fish were slowly fed to the stage and fed, fed and domesticated using feeding measures. After floating on the water, they were grabbed and taken away. Feed station. In general, the 5-6cm long fingerlings that have entered the box in July have been cultured for 8, 9 and 10 months. The average body weight can reach 50-100 grams, and the survival rate is higher in winter.
It is more appropriate for fish species to enter the tank at a water temperature of 15 degrees or more. At this moment, the fish is still in the feeding growth stage, recovers quickly, has fewer diseases, and has a high survival rate. Avoid transporting fingerlings when the water temperature is low during wintering. At this time, the amount of fish activity is small. After entering the cage, the fish is on the one hand, in the state of food and semi-dormant; on the other hand, in order to adapt to the water environment and wind and waves, the physical energy consumption is very large, it is difficult to recover, fish diseases are not easy to treat, and the mortality rate is high. .
Second, daily production management adhere to 24 hours on duty, remember the breeding diary every day (including water temperature, feed amount, fish feeding and activities, dead fish situation), in order to analyze problems and solve problems. Found dead fish removed in a timely manner and sent deep buried shore.
Every 10 days, the cage was pulled to exercise 1 time to increase the activity of the fish and enhance the body mass. At the same time, the sample was weighed and the amount of feeding was adjusted according to the growth of the fish.
Carry out box change and remove attachments from the cage regularly to prevent bacterial infestation and infestation of fish. After being soaked in water for a long time, cages have absorbed fish excreta and waterborne contaminants, and have produced a large amount of filamentous algae, which not only affects the exchange of water, but also becomes a place where Aeromonas hydrophila and other deadly bacteria thrive. , Catfish, live in such an environment can easily cause lesions.
In the aquaculture where the body of the water is relatively fat, large scale, shallow water level and high yield, the work of shifting and arranging is particularly important because the higher the yield, the greater the amount of feed to be fed and the more metabolites released from the fish row, the more The sediments under the tank and the surrounding water environment deteriorated severely. Occasionally, even see floating membranes around the cages, bubbles of toxic gases decomposed out of the water continuously, and the water becomes darker and darker. In this case, immediately move the row upwards to more than 50 meters.
Adjusting the density, although it is suitable for high-density culture, does not mean that the higher the density, the better. Because the number of fish in the same box of catfish is too much, the food is not uniform, the specifications are uneven, and the average increase is slow; the quantity is too small, the food is not fierce, the weight gain is slow, and the utilization rate of the box is low. Therefore, each month in the growing season, the size and quantity of the catfish in each box should be adjusted, or divided or hand-picked, in order to maintain the optimal density and promote its rapid and healthy growth.
Feeding technology
First, the principle of feeding
Insist on feeding and giving people a certain point: Each person is fixed and fed at the same position every day; Feeding is observed to observe the fish’s feeding and activity conditions; Qualitative: To ensure that the feed ingredients are comprehensive, feed is fresh, no mildew, no odor, granular palatability, powder is less ; Timed quantitative: the end of the catfish, there are stomach fish, under normal circumstances each food intake up to 1% -2% body weight, food intake from the body to the discharge takes 6-8 hours; feeding at the same time every day to promote Appetite, to ensure that the relevant digestive enzymes within the fish at the same time reach the highest value, in order to improve feed digestibility.
Second, the feeding method each time when the feeding is less, the interval time is longer, the injection speed is slower, and the number of time when the fish concentrates on food is large, the interval time is short, the feeding is faster, and the feed is late The interval time is longer, ie follow the "less-more-less" and "slow-fast-slow" feeding techniques until 80% of the fish do not feed when they do not rush.
Feed requirements
Forktail tail? 5-6 cm below the partial eclipse zooplankton, such as rotifers, Cladocera, etc.; so it can be used traditional Chinese fertilizer pond method for seedling cultivation. After 5-6 centimeters, it began to be omnivorous, mainly organic shredded shoulders; in the case of intensive culture, it completely relied on compound feed. Therefore, formulating scientific formulas based on the requirements of various kinds of nutrients by the punctures is the key to success.
Protein requirements and essential amino acids. The so-called protein requirement refers to the minimum protein content that can meet the fish's amino acid requirements and achieve optimal growth. The protein requirement for the suitable feed for the catfish stage (8-50 g) is 35%-41%, and the suitable feed protein requirement for the 50 g or more individuals is 25%-35%. The essential amino acids of the catfish tailfish are 10 species like other fish.
energy. Energy is an important basis for animal survival and growth. The index of energy measurement in fish feed is usually based on the ratio of digestible protein (DP) and digestible energy (DE), ie egg energy ratio. The /DE value is 85-114 and the larval stage ratio is higher. When the feed energy is low relative to the protein content, the feed protein is not used for the growth of fish, but is converted into energy to maintain the survival; on the contrary, excessive energy in the feed will reduce the intake of fish and other important substances, resulting in Body fat accumulation.
Minerals. The demand for minerals by fish is partly absorbed by the water from outside the body; it is mainly taken from the feed. The main function of minerals is to participate in the formation of bones, which is an important part of hormones and enzymes, and can regulate osmotic pressure and acid-base balance.
Vitamins. The amount of vitamins needed in animals is very small, but the indispensable essential components in animals play a decisive role in maintaining normal growth, metabolism and reproduction, and in participating in the formation of enzymes in the body.
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