CATDOLL : CATDOLL: What should you pay attention to when raising sea bass in fish ponds?

1. If conditions permit, the pond used for breeding perch should be dried, desilted and exposed to the sun, especially the old ponds that have been used for breeding for many years. Disinfection should be carried out half a month before stocking, and 50 kg of quicklime or 20PPM bleaching powder should be used to disinfect the pond water. If the pond is not dried and exposed to the sun, 30 kg of tea bran should be crushed and soaked in water and sprinkled throughout the pond to completely remove the remaining fierce fish. After disinfection, fresh water is added to the pond through the filter, and 3 kg of compound fertilizer is applied per mu to cultivate plankton. The water quality is slightly green or slightly brown, and the seedlings can be planted.

2. After the intermediate cultivation, the fish have reached 10 cm in length. It is better to stock 2,500 per mu. The yield per mu can reach 1,200-1,500 kg in a 300-day breeding period. If the stocking is too dense, the pond is prone to aging and fish diseases, making it difficult to carry out sustainable production.

Due to high-density farming, a lot of feed is required, and the wide sea bass rarely seeks for leftover bait at the bottom of the pond. Therefore, 100 crucian carp and 30 silver carp and bighead carp should be released per acre to reduce water pollution and increase farming efficiency.

3. Bass are overeaters. Appropriately controlling the amount of feed is conducive to reducing costs, the occurrence of gastrointestinal diseases and water pollution. Feeding should be done at a fixed time, fixed point and fixed quantity. Generally, two meals a day are fed at 7-9 am and 4-6 pm respectively. The daily feeding amount is about 5% of the fish's body weight. It is necessary to adhere to the habit of taming feeding. A bait bridge is built in the pond. Every time you feed, you knock on the bait bridge or splash the pond water to attract the fish to swim to grab food. This is conducive to observing the feeding and health of the fish, and it is convenient to take emergency measures. Bass grabs the suspended feed in the water and stops eating after sinking. Therefore, small fish should be fed patiently and slowly, and granular feed should be floating feed.

4. High-yield breeding of sea bass is also high-density breeding. It is very important to keep the water fresh and the dissolved oxygen sufficient. The main methods are: frequent water changes, especially in the middle and late stages, the daily water change volume should reach more than 30%; frequent oxygenation, the aerator can be properly started in the fry stage, and the aerator should be started more frequently as the fish grows, especially in hot weather and in the late stage of breeding. Some aerators can be started at night, and all aerators should be started during the day to keep the dissolved oxygen content of the pond water above 5 mg/L; biological agents are applied. High-density breeding brings a large amount of residual bait and excrement to the bottom of the pond, and the concentration of harmful substances decomposition is high, which consumes a lot of oxygen in the water, especially in hot weather. It is more serious, which is an important cause of fish diseases. Appropriate application of biological agents allows beneficial bacteria to remove ammonia nitrogen and nitrite in the water and maintain good water quality.

[Things to note when raising seedlings]:

Pay attention to the temperature difference when putting the seedlings into the box. If the temperature difference is greater than 3 degrees, putting the seedlings directly into the box will cause large-scale death.

After the fry are put into the box, they should be disinfected immediately and given drugs to enhance immunity. If parasites are found under the microscope, they should be disinfected immediately.

You can start feeding 3 hours after entering the box, adopting the principle of small amounts and multiple times, feeding 5 to 6 times a day.

It must be screened every 5 to 7 days.

【Precautions for adult fish farming】:

After about 4 to 5 screening and sorting boxes, when the fry are basically more than 3 inches in length, adult fish breeding can begin. At this time, 2500-4000 fry are placed in each box.

During the adult fish breeding period, the feeding amount is maintained at around 1%, and the maximum does not exceed 2%. The feeding frequency should be twice a day. If conditions permit, fresh fish can be added to the feed throughout the process. This can reduce diseases while ensuring good growth of the fish.

【Introduction of sea bass】:

There are four types of fish that can be called perch in Chinese, namely: Sea perch, scientific name Japanese perch, distributed in coastal waters and at the intersection of freshwater and seawater in estuaries. Songjiang perch, also known as four-gilled perch, is a migratory fish and is the most famous. Largemouth black bass, also known as California bass, is a new species introduced from the United States. River perch, also known as red perch and five-way black, is native to northern Xinjiang. This entry focuses on the first type of sea perch (Japanese perch, flower perch), and the other three types of perch will be introduced and distinguished at the end of the entry to avoid confusion. Japanese perch, the commercial name is sea perch, also known as flower perch, seven-star perch, and perch shark, and the local names include Zhaihua, perch board, four-rib fish, etc. It is mainly distributed in the coastal shallow waters of China, North Korea and Japan; it is distributed along the coast of China, likes to live in estuaries, and can also go upstream to the freshwater areas of rivers. In China, the production is relatively large in the Zhoushan Islands in the East China Sea and the Jiaodong Peninsula in the Yellow Sea. It is one of the economic fish and also a species for developing marine aquaculture.

【Distribution range】：

It is mainly distributed in the western Pacific Ocean, my country's coastal areas and freshwater bodies connected to the sea, with more in the East China Sea and Bohai Sea.

[Nutritional value]:

Sea bass contains nutrients such as protein, fat, and carbohydrates. It also contains vitamin B2, niacin, and trace amounts of vitamin B1, phosphorus, and iron. Sea bass can nourish the liver and kidneys, strengthen the spleen and stomach, and relieve phlegm and cough. It has a good tonic effect on people with liver and kidney deficiency, and can also treat fetal movement disorders and postpartum milk deficiency. Pregnant women and postpartum women can eat sea bass to nourish their bodies without causing overnutrition and obesity. In addition, sea bass blood contains a lot of copper, which is an indispensable mineral for maintaining the normal function of the human nervous system and participating in the function of key enzymes in the metabolism of several substances.

【Appearance】：

The body is long, flattened laterally, with a slightly raised back, and the dorsal and ventral surfaces are blunt and rounded; the head is medium-sized and slightly pointed. The body length can reach 102 cm, and the average weight is 1.5-2.5 kg. The largest individual can reach more than 15 kg. The snout is pointed, the mouth is large, terminal, and obliquely cleft. The lower jaw protrudes slightly from the upper jaw, and the upper jaw extends to below the posterior edge of the eye. The two jaws, the vomer and the operculum all have small teeth. The posterior edge of the preoperculum has fine serrations, and the lower edge of its posterior angle has three large spines, and the posterior end of the postoperculum has one spine.

【Edible value】:

Sea bass is rich in protein, vitamin A, B vitamins, calcium, magnesium, zinc, selenium and other nutrients. It has the effects of nourishing the liver and kidneys, benefiting the spleen and stomach, resolving phlegm or relieving cough, and has a good tonic effect on people with liver and kidney deficiency.

Sea bass can also treat fetal movement disorder, low milk production and other symptoms. Eating sea bass is a nutritious food for expectant mothers and pregnant women, which can not only nourish the body but also will not cause overnutrition and obesity. It is an excellent product for body building, blood replenishing, spleen and qi strengthening, and physical health. Sea bass is mostly steamed to maintain its nutritional value.

There is also a lot of copper in sea bass blood, which can maintain the normal function of the nervous system and participate in the function of key enzymes in the metabolism of several substances. People who are deficient in copper can eat sea bass to supplement it.

Sea bass is also known as spotted sea bass and seven-star sea bass. It belongs to the order Perciformes and family Liparidae in taxonomy. Because it breeds and grows along the coast, it is different from the California sea bass and sweet-scented perch that grow in freshwater, so it is also called sea bass.

Sea bass is a ferocious carnivorous fish. It feeds on small fish and shrimps naturally. In artificial breeding, it mainly feeds on high-grade expanded feed and a small amount of fish fry. Sea bass is a euryhaline fish with the characteristics of fast growth, wide adaptability and strong disease resistance. The healthy breeding technology is introduced as follows.

1. Pond requirements and stocking preparation

1) Ponds Each pond should have an area of ​​8-12 mu and a water depth of about 2m. If the pond is too small, the water body is narrow, the dissolved oxygen is insufficient, and it is difficult to produce high yields; if the pond is too large and too deep, it is not conducive to production operations. It is best to set up inlet and outlet gates in the pond, leading to the inlet and outlet rivers respectively, and do not reuse the aquaculture water to avoid secondary pollution.

2)

Mechanical equipment: One aerator is required for every 1.2 to 1.5 mu of water surface, which is a basic condition for high-yield farming. The pond needs to be equipped with a pump to ensure that new water can be replaced at any time, which is even more necessary for ponds without inlet and outlet gates. In addition, a diesel generator is required to prevent power outages and hypoxia in the pond.

3) Pond cleaning: Ponds used for breeding perch must be dried, desilted and exposed to the sun, especially old ponds that have been used for breeding for many years. Disinfection should be carried out once half a month before stocking, and 75kg of quicklime or 0.02‰ bleaching powder should be used to disinfect the pond water. If the pond has not been dried and exposed to the sun, tea bran should be crushed and soaked in water and sprinkled throughout the pond to completely remove wild fish.

4) Use fine mesh to divide the pond into smaller parts to make it easier for the fry to eat.

5) After the water has been cultivated and disinfected, fresh water (about 80 cm) is introduced into the pond through a filter, and some compound fertilizer is added to cultivate plankton.

2. Selection and cultivation of fry

1) Selection of fish fry

The stocking time is from early December to March of the following year. The fry needed for breeding sea bass in Guangdong are basically hatched and desalinated in Fujian and then directly transported to Doumen, Zhuhai for temporary breeding and sale in net cages. They are generally 2~3cm in size.

You must go for big ones, and also pay attention to the "black body" fry, which have a low survival rate due to transportation stress.

2) The stocking density of fry is about 8,000 per mu. The fry are usually released at noon on sunny days (when the water temperature and dissolved oxygen are high, which can reduce the discomfort of the fry). The fry are disinfected with water and then placed in the prepared grid. Due to the high-density breeding, a lot of bait is added, and the perch rarely eats the leftover bait at the bottom of the pond. Therefore, after the nets are removed, a small amount of crucian carp, tilapia or bream (omnivorous) should be added per mu, and a small amount of silver carp (filter feeder) should be added to reduce water pollution and increase breeding benefits.

3) After the fry are released, sufficient oxygenation should be provided (it is best to use air stones to provide oxygen at the bottom). Generally, no feed is given on the first day. After one day, feeding training should be gradually started. It is required to be fed at a fixed time and place, generally four meals. Water spider is the best starter bait, or fish paste can be mixed with part of eel feed. When the fry are 5~6cm, expanded feed can be gradually fed. Anti-enteritis drugs should be appropriately added to the feed for the fry. As the fry grow gradually, the grids will be gradually removed.

3. Management and disease control

1) Daily management

(1) Bass are prone to overeating when fed, so the amount of feed should be appropriately controlled to reduce costs, the occurrence of gastrointestinal diseases and water pollution. Feeding should be done at a fixed point, time and quantity. Generally, two meals are fed a day, at 6-7 am and 6-7 pm respectively. Generally, a bait bridge is built in the pond. It is advisable to feed until the fish are 80% full each time. In case of high temperature or changeable weather, the amount of feed should be appropriately reduced. Pay attention to the eating and health status of the fish each time you feed, so that emergency measures can be taken in time.

(2) Water quality management High-yield breeding of sea bass is also high-density breeding. It is very important to keep the water fresh and the dissolved oxygen sufficient. The main methods are: first, change the water frequently, especially in the middle and late stages; second, increase oxygen frequently. The aerator can be started appropriately during the fry stage. As the fish grows, the number of times the aerator is started becomes more and more frequent, especially in hot weather and in the late stage of breeding. All aerators should be started to keep the dissolved oxygen in the pond water sufficient; third, biological agents should be applied. High-density breeding brings a large amount of residual bait and excrement to the bottom of the pond. The concentration of harmful substances decomposes to a high level, which consumes a large amount of oxygen in the water, especially in hot weather. Appropriate application of biological agents can effectively degrade ammonia nitrogen and nitrite and maintain good water quality. In addition, disinfection and pest control should be done well. Generally, disinfection should be done once every 15 days, and the frequency depends on the fish's feeding situation.

(3) During the day, the main observation of the increase or decrease in the amount of food consumed is used to determine the health of the perch. Generally, the first sign of discomfort in fish is their food consumption. In addition, check whether there are any fish swimming. Before a large number of fish succumb to the disease, there are usually only a few fish swimming. This is the best time to see a doctor and take medicine, and it is also the critical period. At night, especially between 2 and 3 o'clock in the middle of the night, the operation of the aerator should be inspected. Anti-theft: Fish theft incidents occur every year, so anti-theft must be paid attention to in the middle and late stages of breeding. The general method is to keep the fish pond well lit at night, set up fences in the fish pond, and install monitoring equipment if conditions permit.

2) Disease prevention and control

(1) Ammonia nitrogen and nitrite poisoning In hot weather, the ammonia nitrogen in the water is high, and even nitrite is produced, which will cause the perch to be poisoned by hypoxia and eat less food, resulting in fish death. Main symptoms: dark red gill filaments, reduced food intake. Prevention and control methods: Apply flocculants to absorb ammonia nitrogen in the water, and apply bottom treatment agents to reduce ammonia nitrogen; release some old water and inject new water. When injecting water, avoid directly flushing the dirt on the bottom of the pond to accelerate the death of fish;

Many fishermen who work in the scallop and shrimp ponds in Xiangshu Bay have not made good profits. In addition to the impact of climate change, the main reason is problems in technical operations. To improve the economic benefits of scallop and shrimp ponds this year, we should focus on improving the quality of commercial seedlings and the survival rate of seedlings, and get rid of the following six misunderstandings.

1. The shrimp pond environment is not suitable and the water depth is less than 1.2m

, the daily water exchange capacity is less than 10%; the shrimp pond bottom is soft mud, the pond edge is not compacted, and the pond water is easily turbid in strong winds

Turbidity blocks the mesh of the seed bag; premature fertilization causes the bait in the pond to age, and the hook shrimp or protozoa reproduce in large numbers; the area of ​​the shrimp pond does not match the number of seedlings, and the seedling density is too high, resulting in a shortage of bait in the later stage. These factors can affect the growth rate of shellfish seedlings and reduce the survival rate.

2. The spat are taken out of the pond too early and blindly pursue early seedlings. After the spat enter the shrimp pond, the water temperature is below 13℃ for a long time and is unstable. The spat have low metabolic intensity and grow slowly. If they fall off, it is difficult to reattach. Once there is cold air activity, the water temperature may even drop to around 8℃, causing the spat to be in a closed shell state, thus affecting their growth and survival.

3. Poor quality of juvenile spat. Juvenile spat with a size of less than 400μm, poor feeding, poor vitality, loose attachment, and without cooling and light training, often cannot adapt to changes in the external environment after entering the shrimp pond, and the survival rate of the spat is extremely low. We should pay attention to asking about the source and specifications of the broodstock, the time for ripening, the cultivation conditions, the use of drugs, the types of feeding, etc., and combine microscopic examination, naked eye observation, swing test, cooling test and other methods to check the spat attachment, feeding, vitality, size and other indicators, and make a comprehensive evaluation of the quality of juvenile spat.

4. The main reason for inaccurate counting of spat out of the pond is that the sampling is not representative. In the densely attached areas, more points are taken, and in the non-dense areas, no or less points are taken. At each point, only the water layer or part with more attached spat is sampled. The total number of attachment bases includes the bottom curtain, but it is not taken during sampling. Secondly, there is even tampering during counting, and the number of attachment bases is deliberately overreported. These phenomena lead to the counted number far exceeding the actual number of spat in the nursery pond. Therefore, for nursery ponds below 20m3, at least 4 to 5 points should be sampled, and for large ponds, more than 6 points should be sampled, and the number of eye-point larvae and metamorphosis rate should be used as reference.

5. Rough daily management, failure to flush the floating mud from the seedling bag in time, resulting in poor exchange of water quality and bait inside and outside the bag; failure to timely empty the bag, crowding the seedlings in the bag, polarization, and weakening; excessive movement during operation, washing off the bag wall and the attachment base, piling up in a corner of the seedling bag, biting each other to death. Secondly, when the seedlings are separated, the shellfish are trapped in the plastic basin for a long time due to lack of oxygen, and the drying time is too long, so they cannot be dispersed and attached to the seedling bag again for a long time after separation.

6. Water quality deteriorates. During the seedling period, the daily water change rate should be gradually increased as the fry grows. When protozoa reproduce in large numbers or the algae age and die, causing a sudden change in water color, water should be changed immediately. The transparency should be maintained at 60-80 cm. If it exceeds 80 cm, inorganic fertilizer should be applied in appropriate amounts. If the seedling period exceeds 25 days, it will enter a dangerous period. At this time, the water temperature rises and the bait is often unable to meet the feeding needs of large-sized fry, thus affecting the secretion of byssus threads and easily causing large-scale deaths. It is recommended to release them into the sea in time. Six misunderstandings about the seedling protection of bay scallops in shrimp ponds. (2) Enteritis disease: The abdomen of sick fish is swollen, the anus is red and swollen, and yellowish mucus flows out when the abdomen is squeezed. It is mainly caused by feeding spoiled feed or overfeeding. When treating, first reduce the feed (it is best to stop feeding for one meal), and feed with broad-spectrum antibiotics mixed with bait for 3-5 days, which generally cures the disease. (3) Hemorrhagic disease: The base of the pectoral fin and dorsal fin of sick fish is red, swollen and congested, and the sick fish moves slowly and eats less. This disease is a viral infection and is highly contagious. For treatment, a mixture of virulin and norfloxacin can be used to feed the fish for 6 consecutive days. At the same time, strong chlorine can be sprayed throughout the pond once a day for 3 consecutive days. (4) Saprolegniasis This disease often occurs in winter and spring when the water temperature is low. Grayish-white cotton-like mycelium is attached to the wounds on the surface of the diseased fish. The fish becomes weak and slowly dies. This disease spreads quickly after infection. Prevention can be achieved by pumping some groundwater to maintain salinity and adding more water to maintain water temperature. This disease is prone to occur under specific conditions. Changing the pond water environment and maintaining adequate nutrition for the fish to improve disease resistance are the most effective control measures. (5) Wheelworm, oblique tube worm, and polycystic ovary disease often occur on the body surface and gill filaments of fish in the intermediate breeding stage. Symptoms include weight loss, black body color, and erosion at the mouth. The disease occurs all year round. Prevention often uses water replacement to improve water quality. Treatment can be achieved by spraying 0.02~0.025‰ formalin throughout the pond. Generally, parasites are prone to cause secondary bacterial infections, so disinfection is generally required after killing the insects. (6) Hepatobiliary syndrome is mainly manifested by reduced food intake, gradual swimming of fish, and unexplained deaths. The main reason is that drugs are frequently applied under high-density breeding, and toxic and harmful substances in the water are chronically accumulated in the fish, leading to organ dysfunction and tissue damage in the fish; long-term overfeeding and long-term overload of the fish liver lead to metabolic disorders or even metabolic disorders. Prevention and control mainly involves regulating the water environment, feeding scientifically, and regularly mixing feed with some liver-soothing and gallbladder-promoting Chinese herbal medicines to have a certain preventive effect.

The role of Huijunju EM active bacteria in aquaculture

* Control the content of harmful substances such as ammonia and hydrogen sulfide in the water environment and regulate the microbial ecological structure of the breeding pond;

* Enhance the immune function of aquatic animals, prevent diseases, improve health, and reduce morbidity and mortality;

* Promote growth, weight gain and increase yield;

* No pollution, low cost, great effect, improve meat quality;

* Purify water quality, improve environment and extend water change interval.

* Reduce pathogens, balance the microecology, reduce the use of drugs, and ensure environmental safety;.

Water quality, temperature, microorganisms in water