CATDOLL : CATDOLL: Hello! What is the stocking density of silver carp without feeding, only fertilizer. If you put one pound of silver carp in May, the fish will be able to grow big after the August Festival.

1. Hello! What is the stocking density of silver carp without feeding, only fertilizer. If you put one pound of silver carp in May, the fish will be able to grow big from the August Festival.

Without feeding, the breeding capacity of silver carp is about 200 per acre.

The fry, weighing about one jin, are released in May and harvested in August, but most of them can only grow to two jin.

We also have to take into account the hot weather in May, so the mortality rate of large fish fry weighing one kilogram is relatively high.

You can also open a small pond to use pig manure to ferment zooplankton, and then catch the zooplankton to feed the silver carp and kaipai fish.

2. How big is a pound of silver carp after 5 months?

Two catties. A one-catty Hualien fish fry is released in May, and five months later, when it is harvested in October, it can only grow to two catties at most. This is the normal growth rate of Hualien.

3. What is the approximate survival rate of silver carp through artificial breeding?

First of all, we have to look at the weather and water temperature: I personally think that the critical water temperature for silver carp is 16 degrees Celsius. Below 16 degrees Celsius, bighead carp and bighead carp are in danger of death. The water temperature is between 16 and 18 degrees Celsius, and they are in danger of death. Even if they are lucky enough to survive, they grow very slowly, and then they will become thin and die due to lack of food. The final survival rate is generally not high, and it is not recommended to rush for success. There are two ways to release fry: winter and spring. Winter release means that after the fish pond is fished, the original fish pond is cleaned, repaired and detoxified. After a period of time, the temperature is colder and the fry have entered a fasting period. Released fry can survive the winter safely. The other way is to start releasing fry in March after the spring.

Silver carp grows faster than bighead carp. In natural rivers and lakes, individuals weighing more than 10 kilograms can be seen. It is suitable for breeding in fertile ponds. The time for releasing fish fry should be planned. The time period for releasing silver carp can be selected in April and October. These two seasons are most helpful for the early growth of silver carp. The number of silver carp released each time should be gradually reduced, and the male-female ratio of the prepared fish should be controlled. The number of silver carp released per acre can be controlled at about 1,000.

Silver carp mainly refers to freshwater bighead carp and silver carp (also called flower carp). Almost all silver carp mainly filter feed on ephemera, among which silver carp mainly filter feed on algae and other ephemera, and its gill rakers are relatively dense; silver carp mainly filter feed on ephemera or gnats, and its gill rakers are relatively loose. There are no wild fish for sale in the market now, and if there are, they are some lies. I am telling the truth. In our rural areas, whether it is a large reservoir area or a collective pond, they are all contracted by someone. From large reservoirs to small ponds, fish are raised. The water is turbid and black, mainly because of the long-term water quality corruption caused by the feeding of flavored feed.

It is really difficult to judge whether silver carp and carp are artificially farmed or wild. For example, those raised in fish ponds without feeding are considered wild or farmed. There are currently very few silver carp and carp in rivers and they are basically not sold in general vegetable markets.

The survival rate of silver carp through artificial breeding is about 80%, which is still considerable. As long as the breeding is done well, the mortality rate will not be high.

If the artificial breeding method is correct and the breeding environment is suitable, the survival rate is about 70%.

It is relatively easy to raise, and the survival rate is about 90%. However, the density must be controlled well, and some nutritious feed must be fed.

There should be a probability of about 80% in the future. Generally, in an artificial breeding environment, a more favorable environment will be created, making it easier to grow.

4. How to breed garfish?

Efficient breeding of yellow catfish starting with bait

Yellow catfish, also known as yellow catfish and garfish, is a small freshwater economic fish. It is omnivorous, has strong adaptability, has low requirements for water quality, is easy to introduce and domesticate, and is increasingly favored by consumers due to its high nutritional value. It is also an excellent variety suitable for eating and fishing to improve the structure of aquaculture varieties. In recent years, we have continuously conducted small pond main breeding experiments and achieved good results. The key link of bait technology for efficient breeding of yellow catfish in small ponds is introduced as follows:

1. Bait preparation

The food of yellow catfish in natural waters is mainly shrimp, fish, fish eggs and some aquatic insects. Aquatic plants, etc. Therefore, fresh animal bait can be used for artificial breeding. In recent years, we have adopted homemade compound bait for domestication and feeding. The bait is made of imported fish meal, meat and bone meal, blood meal, soybean meal, rapeseed meal, dried fish worms, etc. and feed additives. The protein content is more than 34% and the fat is 4% in the early stage; in the later stage, small fish meal can be used to replace part of the imported fish meal, with a protein content of 30% and a fat content of 6%. The feeding bait must be fresh and free of mold and rancidity.

2. Domestication

Wild yellow catfish like to hide during the day and come out at night to feed. Under artificial breeding conditions, after 5-7 days of domestication, they can go to the feeding table to feed during the day. Two days after the seedlings are put into the pond, they are domesticated by artificial feeding. During the domestication, fixed feeding signals are used to carry out fixed-point and regular feeding training. After 5-7 days of patient domestication, they can be fed normally; the domesticated seedlings put in this way can be fed normally on the second day after entering the pond. The feeding method can be artificial or mechanical feeding.

3. Feeding amount

The entire feeding process should be divided into three stages. In the first stage, feed 4 times a day in May and June, with a daily feeding rate of 3%-5%; in the second stage, feed 3 times a day in July, August and September, with a feeding rate of 2%-3%; in the third stage, feed twice a day after October, with a feeding rate of 2%. On this basis, the amount of feed should also be adjusted according to the weather and water quality. In the first and third stages, it is recommended to use the satiation method, that is, stop feeding after 90% of the baited fish leave the platform; in the second stage, due to the hot weather and the fluctuating water quality, it is recommended to feed "90% satiation", that is, stop feeding after 80% of the baited fish leave the platform.

In addition, due to the large mouth of yellow catfish, the particle size of the bait should be increased accordingly. The particle size of 2.0 mm is used as the starter feed, and the particle size of the adult fish feed can reach more than 5 mm. The use of sinking hard granular bait requires the particles to be stable in the water for 15 minutes; the use of floating bait will better improve the utilization rate of bait.

------------------------------------------------------------------------------------------------------------------

Intensive culture technology of yellow catfish in ponds

Yellow catfish belongs to the order Siluriformes, family Peltocatus, genus Pelteobagrus. In some places, it is also called yellow latin, yellow yagu, yellowfin fish, and agarfish. It has bright color, tender and delicious meat, rich nutrition, no intramuscular spines, high edible rate, strong vitality, and a wide range of temperature adaptability. It is a new type of breeding species that can be developed. Its biological characteristics and pond intensive breeding technology are introduced as follows:

1. Biological characteristics

1. Morphological characteristics: long body, broad and flat head, raised back, flat abdomen, slightly flattened posterior part of body, short and thick caudal peduncle, large mouth, lower jaw shorter than upper jaw with fine teeth, 4 pairs of whiskers, small and laterally located eyes, dorsal and pectoral fins with hard spines with serrations, pectoral fins slightly fan-shaped, end close to pelvic fins, caudal fin deeply forked, adipose fin shorter than anal fin, anus located between pelvic and anal fins, naked body without scales, back of body dark brown to bluish yellow, abdomen light yellow, body color varies with habitat.

2. Diet: It is a generalist fish, and its food includes various aquatic insects, small fish and shrimps, small mollusks and other invertebrates.

3. Growth and reproduction: Under natural conditions, the body length of a one-year-old fish can reach 8cm, and that of a two-year-old fish can reach 16-20cm. The largest individual can reach more than 500g. Generally, sexual maturity can be achieved at the age of two. Generally, sexually mature males are larger than females. The spawning period is from May to July, and the fish spawns multiple times a year. During the reproductive period, male fish have the habit of building nests and protecting eggs and fry. The suitable water temperature for breeding is 23-30℃, and each fish can carry 2000-3600 eggs. Eggs are usually laid at night. The fertilized eggs are slightly yellow and sticky, with a diameter of about 2mm. The water temperature is 23-28℃, and the fry can emerge after 50-60 hours of incubation.

2. Pond culture technology

1. Pond preparation: The size of the pond for breeding yellow catfish is generally 2000-3500m2. The bottom of the pond should be flat, but the drain end should be slightly lower than the inlet end (the slope should not be too large). Dig a 50-60m2 fish collection pit with a depth of 20-40cm to prepare for fishing in the dry pond. The pond water source should be sufficient, the water quality should be fresh, the water inlet and outlet should be convenient, and the water depth can be maintained at 1.5-2m. The planned output is above 150kg/667m2, and a 2kw aerator should be equipped; eliminate excessive silt and keep about 10cm; use 150kg of quicklime dry method to clean the pond for every 667m2 of water surface, try to mix the bottom sludge with lime, and expose it to the sun for 1 week and fill 80cm with water; apply 100-200kg of fermented organic fertilizer for every 667m2, and when a large number of plankton are cultivated, fish can be released.

2. Stocking of fish: Stocking time is generally from March to April, and the stocking density is flexibly controlled according to the pond conditions, management level, feed and expected specifications of the fish to be released from the pond. Fish with neat specifications, bright colors, smooth and uninjured body surface and strong physique should be selected for stocking. Generally, 2,000 to 4,000 yellow catfish fry with a body length of 5 cm are stocked per 667m2. If the fish are about 30g, 1,500 to 3,000 are stocked per 667m2. Before stocking, the fish are soaked in 5% salt water for 10 to 15 minutes, and the use of strong oxidizing drugs such as potassium permanganate is avoided as much as possible. 15 to 20 days after stocking yellow catfish, 200 to 400 silver carp with a body length of 10 to 15 cm are stocked per 667m2 of water surface.

3. Feeding: Under artificial breeding conditions, small fish and shrimp, animal waste can be used for feeding, and fish meal, meat and bone meal, blood meal, soybean meal, feed additives, etc. can also be used to make pellets for feeding. The protein content is 30% to 40%, and the fat content is 4% to 6%. In the hot season, an appropriate amount of bacitracin zinc can be added, which can effectively prevent and treat a variety of diseases, relieve a variety of stress phenomena, and promote growth and reduce the feed coefficient. However, it should be noted that it cannot be used with colistin sulfate and furazolidone. Wild yellow catfish likes to forage at night, and after 5 to 7 days of domestication, they can feed normally in groups. If the fish species released are artificially propagated seedlings, they can be fed normally on the second day after entering the pond. After normal feeding, the feeding rate is 1% to 3% before April, and 4% to 6% during the peak growth season. Feed once in the morning and afternoon every day. Feeding should be done in four fixed ways.

4. Daily management: In the process of breeding yellow catfish, water quality management is the key. From May to June, water should be added once a month, with a depth of 30cm. From June to September, water should be added once every half month, with a depth of 20cm. In the hot season, 15g/m3 of quicklime should be sprinkled once a month, and the aerator should be started at the right time. Pay attention to frequent pond inspections, frequent observations, frequent weed removal, and frequent record keeping. Yellow catfish is a scaleless fish with low tolerance to commonly used drugs. When preventing and controlling fish diseases, try to use high-efficiency and low-toxic drugs. This fish species is sensitive to drugs such as malachite green, copper sulfate, trichlorfon, and potassium permanganate, so they should be used with caution.

------------------------------------------------------------------------------------------------------------------

Biology and artificial breeding technology of Pelteobagrus fulvidraco

1. Development prospects of yellow catfish farming

The meat of yellow catfish is tender, delicious and nutritious. According to analysis, every 100 grams of edible part of yellow catfish contains 16.1g of protein, 2.1g of fat, 2.3g of carbohydrates, 154mg of calcium and 504mg of phosphorus. It contains a variety of essential amino acids for the human body, especially glutamic acid and lysine. According to medical history books, yellow catfish has anti-inflammatory and analgesic effects.

2. Biological characteristics of yellow catfish

1. Classification and status

Pelteo bagrus fulvdrace (Richardson) is a freshwater economic fish with a wide distribution in freshwater bodies in my country. It is commonly known as: Ga Ya Zi, Huang La Ding, Huang Fin Fish, etc., English name: Yellow catfish, in fish classification, it belongs to the order Siluriformes, family D, genus Pelteo catfish. There are 4 species in this genus: Pelteo bagrus fulvdrace, Yellow Catfish (Yellow Catfish), Glossy Yellow Catfish, and Forked Tail Yellow Catfish. At present, the main breeding target is Yellow Catfish, followed by Yellow Catfish (both species have seedlings in this farm, and the latter two species have little breeding value due to their small individuals).

(II) Living habits

The fish of the genus Pelteobagrus are benthic fish. They like to live at the bottom of the water body during the day and swim to the upper layer of the water body to feed at night. They have strong adaptability to ecological environment conditions. According to relevant data, when the water temperature is 28-29℃, its average oxygen consumption rate is 0.141mg/hour and its apnea point is 0.314mg/L. It has strong adaptability in low-oxygen environment. In winter, even after leaving the water body for several hours (as long as a certain humidity is maintained), it can still survive. Sometimes in late autumn and early winter, when people transport Pelteobagrus to the market for short-distance sale, they use a layer of aquatic plants on the bottom of bamboo baskets, put Pelteobagrus on them, and then put water plants to maintain humidity for transportation. After a few hours, all the fish can survive when they are put into the temporary aeration pond in the market. Pelteobagrus often lives in an environment with slow river flow, many rocks or pebbles. In autumn and winter, it often hibernates in deep rivers, lake caves, rock caves, and stone crevices at low temperatures. Its activity range is small and it is not easy to catch. In mid-spring, they start to leave their wintering sites and move to nearby rocky shallows and rocks to feed. During the day, they mainly live and move among rocks or pebbles in deeper water, and at night they swim to rocks in shallow waters to hunt. At dawn, you can often see yellow catfish hurriedly looking for caves and cracks to hide in. When rivers, lakes, and reservoirs are flooded in summer, the water becomes turbid. During this period, yellow catfish mostly swim to wide chamfers to feed on mosquito larvae brought or grown in the water. In autumn and winter, as the water of rivers and lakes becomes clear and the water temperature drops, they gradually swim to deep rocky rivers and deep holes in lakes to feed. Yellow catfish like to gather in groups and feed and move under weak light conditions.

3. Food habits

Yellow catfish is an omnivorous fish. Its feeding habits vary significantly with the size of the individual. It starts to eat zooplankton, such as rotifers, copepods and cladocerans, as well as artificially fed egg yolks, from the 4th to 5th day after the eggs hatch. Its body length is 5-8cm. Its main food is cladocerans, copepods, chironomid larvae, water earthworms and artificially prepared mixed feed (fish paste and plant feed mixture). When its body length is more than 10cm, its main food is: snails, shrimps, small fish, chironomid larvae, larvae of Ephemeroptera, larvae of Coleoptera, insect eggs, green water spiders, bitter vegetable leaves, Malaysian pondweed leaves, polyphylla leaves, plant fibrous roots and debris, fish scales, mud and sand, and fish eggs laid by other fish on aquatic plants and stones. Under artificial breeding conditions in ponds, in addition to eating natural bait organisms in the pond, they must generally be fed artificially prepared soft compound feeds. They can also be fed hard granular feeds and floating feeds. Especially under intensive cage flow-through breeding conditions, the protein content of the compound feed must reach 35-40%.

3. Fish breeding

The commercial fish breeding of yellow catfish is called adult fish breeding, which refers to the production process of using fish species over 2cm to breed commercial fish. At present, most of the commercial fish sold in the Chinese market come from natural water bodies, and some are obtained from adult fish ponds. In recent years, many experts (including ours) have begun to actively carry out research on artificial pond main breeding and mixed breeding of yellow catfish, and have obtained a series of relatively mature technical data, especially in large-scale artificial breeding of fish fry. There have been major breakthroughs, thus alleviating the contradiction of tight seed supply. Experimental studies have shown that yellow catfish is suitable for breeding in ponds, cages, large and small lakes, rice fields and other water bodies. It can be raised as the main breeding and can be mixed with silver carp, bighead carp, bream, grass carp, etc. However, it is not suitable to be mixed with carp, crucian carp, etc., because their feeding habits are basically the same and it is easy to have adverse effects.

(I) Ponds mainly raise yellow catfish

Pond farming is a new type of farming method that has only emerged in the past two years. Pond farming has the characteristics of small investment, no restrictions on area size, high returns, and stable productivity.

1. Pond conditions

① Water source and water quality. The main pond for raising yellow catfish requires sufficient water source, water quality that meets the water quality standards for fishery water, and does not contain substances harmful to fish. It is best to choose a fish pond close to a reservoir, lake, river, or ditch, or a fish pond equipped with mechanical equipment such as aerators and pumps to raise yellow catfish. The main stocking density in the pond is high, and the water quality is often easy to deteriorate due to the low dissolved oxygen content in the pond water, causing fish to float and a large number of deaths. If conditions permit, frequently adding new water with high oxygen content can not only improve the water quality of the pond, but also facilitate the reproduction of natural fish bait and the growth of fish.

② Fish pond area, water depth and bottom quality Yellow catfish is not very strict about the requirements of adult fish breeding ponds, and both large and small fish ponds can be used to breed adult fish. It is best to choose a pond with a bottom that is 10% to 20% deeper than other places at the outlet of the pond. It is mainly convenient for commercial fish dry pond fishing and each pond must have a controllable inlet and outlet. The main breeding pond area is generally 3-5 mu or less than 10 mu. The water depth of 1.5-2.0m is ideal. The pond is shallow and the light intensity is strong, which is not conducive to the requirement of yellow catfish to feed under weak light. Practice has shown that sandy soil is the best for the bottom quality of the pond, and clay and less muddy ponds are also acceptable. The bottom silt cannot be too thick, about 10cm is enough, and it is required to have strong water and fertilizer retention, rapid decomposition of organic matter, and easy fertilization of the pond water.

2. Stocking density

The stocking density of yellow catfish in ponds is related to factors such as pond conditions, environmental factors, fish species specifications, feeding level, water source and consumption habits. In the south of the Yangtze River, the stocking rate is 8,000-10,000 fry per mu with a total length of 2 cm, 6,000-9,000 fry per mu with a total length of 3 cm, and 4,000-6,000 fry per mu with a total length of 4-5 cm. When the yellow catfish to be stocked grows to a body length of about 7-8 cm, the water quality has begun to become rich. At this time, about 200 silver carp and bighead carp are put into each mu. The size is 2-3 inches to control the water quality in the yellow catfish pond. The seedlings of the year can be grown into commercial fish with a size of 100-150g. The yield per mu can reach 300-400kg, or more than 800kg (pond conditions and bait ideal).

If the pond conditions, water sources and oxygenation equipment are better, the stocking amount can be increased by 50%-100%.

3. Feed and feeding

The feeds used to raise adult yellow catfish include two types: pure animal feed and artificial compound feed, which depend on the resource conditions in each area.

(1) Pure animal feed: including small fish, shrimp, terrestrial earthworms, etc. These feeds are what yellow catfish like to eat, but the sources vary from place to place. Some places have more abundant resources, while others have more limited resources. Generally, most breeders process small fish and shrimp into fish paste and feed them directly. In some places, small fish and shrimp are minced into paste and mixed with plant powdered feed before feeding. The method is to first mix the dry powdered feed for use. The standard is: 10% fish meal, 30% soybean meal, 10% corn meal, 25% third-grade flour, and 1% each of vitamins and inorganic salts. When feeding, add the powdered feed to the fish paste and stir it into a ball before use.

(2) Artificial compound feed: The nutritional requirements of commercial yellow catfish compound feed are 38-40% crude protein, 7-9% fat, 20-23% carbohydrates, and 5-6% cellulose. The animal raw materials of commercial yellow catfish feed include fish meal, silkworm pupae, meat and bone meal, feather meal, blood meal, bacterial protein powder, yeast, etc., and the plant raw materials include soybean cake, cottonseed cake, corn and wheat flour, etc. After crushing, the feed is processed into particles with a diameter of 1.5-2mm according to the formula, and then dried and stored for use. The formula of its adult fish feed is: fish meal 28%, feather meal 5%, meat and bone meal 5%, blood meal 8%, feed yeast 5%, soybean meal 14%, corn meal 3%, vegetable oil 2%, wheat flour 20%, vitamin mixture 1%, and inorganic salt additives 2%.

(3) Feeding: Feeding is a key technology in feeding. The so-called scientific feeding method is to adjust the feeding amount, feeding time and feeding type in a timely manner according to the different species of fish and changes in environmental factors. It is necessary to not only meet the fish's demand for nutrients in a balanced manner, but also to give full play to the maximum utilization rate of feed. It is best to use the domestication method to feed in groups on the water surface like carp, grass carp and crucian carp.

4. Daily management of feeding

The daily management of ponds must be meticulous and long-lasting. The management scope mainly includes feeding management, water quality management, daily management and fish disease prevention and control and other technical measures.

(ii) Flowing water breeding

Pelteobagrus fulvidraco is a fish suitable for intensive breeding. In recent years, some places in my country have mixed it with other fishes for running water breeding. Some places have also initially used the water drop of reservoirs and waste water from factories for breeding, especially in small ponds for micro-flowing water breeding. The yield has reached 30-50kg per cubic meter of body, and can be higher.

1. Flowing pool conditions

According to the characteristics of the feeding and activity habits of yellow catfish, it is suitable to be raised in rectangular cement (the bottom of the pond must be hard mud or sandy) and small ponds. Water flows in continuously from one end and flows out from the other end. Its specifications are determined according to its conditions, and its size can be suitable. The water flow rate is generally kept at a flow rate of 5mg/L of dissolved oxygen in the water pool.

2. Fish stocking

The size of fish in the flowing water pond is about 5 cm, and 300-400 fish are placed in each cubic meter of water. When putting the fish, the fish bodies should be strictly disinfected with 3% salt before being put into the flowing water pond.

3. Bait and feeding

The key to running water breeding is to feed full-price compound feed with a protein content of 40-48%. The feeding method is to set up a certain number of feed platforms on both sides of the running water pool. There must be 1.5O feed platforms for every 10O. The feed platforms should be built about 5-10cm high on the bottom of the pool. The feeding amount varies according to the water temperature. Generally, when the water temperature is 12-18℃, the feeding amount accounts for 2.5% of the body weight. When the water temperature is 18-25℃, the feeding amount accounts for 3-3.5% of the total body weight. When the water temperature is 25-30℃, the feeding amount accounts for 4-5% of the total body weight. Feed more in the morning and evening, and less at noon and when the light is strong.

4. Feeding and management

The water source used for running water must not carry pollutants, the dissolved oxygen content must be above 5mg/L, and the pH value must be 7.0-8.5. The feed should not be excessive to avoid affecting the water quality. Fish disease prevention and control must be carried out regularly. The fish carrying capacity per cubic meter of water is generally maintained at around 30kg.

(III) Pond culture

When yellow catfish is mixed with other species in ponds, the usual method is to directly culture 2-3cm long seedlings in the pond to increase the yield of high-quality fish in the pond and the economic benefits. There are two ways: one is to culture about 300 seedlings over 2cm long per mu in the conventional breeding pond. No feed is given; the other is to not put carp and crucian carp in the conventional breeding pond. Instead, 500-600 yellow catfish are put in.

1. Fish pond conditions

The ponds for raising yellow catfish must be free of pollutants and cannot be raised in environments with domestic sewage. The ponds have escape prevention equipment, a pH value of 7-8.5, dissolved oxygen of 4mg/L, and abundant natural bait resources (such as zooplankton, water earthworms, small fish and shrimp, aquatic and terrestrial insects, etc.).

2. Planting density

The density of mixed culture should be determined according to the bait conditions. In general commercial fish ponds that feed artificial bait, 300 fish are raised per mu. The yield is 30-40 kg. In ponds without carp and crucian carp, 500-600 fish are raised per mu. The yield is 60-80 kg. The seedlings of the culture are generally required to be more than 2 cm long.

3. Management of breeding

For the management of yellow catfish, the dissolved oxygen in the water should be kept above 4mg/L, and the anti-escape work in the pond should be done well to prevent the yellow catfish from escaping. Attention should be paid to the drugs used to prevent and treat other fish diseases that affect the normal growth and death of yellow catfish. It is best not to hook yellow catfish before it grows to about 100g, because yellow catfish are easier to be hooked when the hook is swimming.

4. Disease prevention and control

During the breeding process, disease prevention and control of yellow catfish is more important. While increasing the yield per unit area and increasing the stocking density to expand the breeding area, a series of epidemic diseases may occur. The harm of fish diseases has been found in the breeding of seedlings and adult fish. Therefore, strengthening disease prevention and control is an important management measure to improve the survival rate and yield.

1. Causes of disease

1. The fish pond has not been disinfected, or the disinfection process is not strict, or the disinfectant is ineffective.

2. The stocking density of seedlings is too high, the water quality deteriorates, and the fish's disease resistance is reduced.

3. Live baits such as water fleas and earthworms fed to fish have not been disinfected and have brought in pathogens; or these baits have an enrichment effect on heavy metal ions, and fish become sick after eating a large amount of such live baits; or fish diseases are caused by feed corruption, uneven feeding, or improper fertilization.

4. The fish have poor physical condition, or are injured during transportation, pathogens invade, or the seedlings themselves are already sick.

5. Seedlings and tools are not disinfected, which may bring in pathogens.

6. Poor water source, or cross-infection from diseased and dead fish.

(II) Preventive measures

1. Clean the fish pond thoroughly and disinfect it strictly.

2. When stocking seedlings, first disinfect them by bathing them with furacilin solution and 2-3% salt solution.

3. Stock healthy, large and disease-free seedlings.

4. It is best not to feed live baits such as water fleas and earthworms caught from urban sewage culverts and drainage ditches. Instead, use the method of artificially cultivating live baits.

5. Do not feed spoiled feed, implement the "four determinations" and "four observations" feeding rules, and put fertilizer into the pond only after it is fully fermented and decomposed.

6. Investigate and summarize the types and patterns of fish diseases in the area, and take effective preventive measures. Regularly sprinkle quicklime, trichlorfon, chloranil, copper sulfate, etc. in combination with oral medications, and disinfect live baits, feeding tables, and feeding areas. One of the most effective measures to prevent diseases in cage-reared yellow catfish is to set the cages in open water areas with certain wind and waves or flowing water conditions. The density of cages should not be too large, and it is best to move the cages frequently during the dry season.

(III) Tolerance of yellow catfish fry to several commonly used drugs

The 24-hour half-lethal concentration of common aquatic drugs for yellow catfish is: copper sulfate 0.69mg/L: 90% crystal trichlorfon 2.8mg/L; salt 2.5%; malachite green 0.15mg/L; formalin 68mg/L; ammonia-T 8.4mg/L: yellow catfish's tolerance to common aquatic drugs is not as good as that of the four major fishes. This may be due to the fact that yellow catfish is a scaleless fish and the drugs are more likely to penetrate directly into the body through the skin. Therefore, when using drugs for yellow catfish, its dosage must be strictly controlled to prevent acute and chronic poisoning leading to death. It is relatively sensitive to malachite green, copper sulfate, mercurous nitrate, potassium permanganate, trichlorfon, etc., and should be used with caution.

(IV) Prevention and treatment methods for several common and frequently occurring diseases

1. Hemorrhagic edema

(1) Pathogen: According to preliminary research, the pathogen is bacterial.

(2) Symptoms: The fish's body surface turns yellow, and the mucus increases; the pharyngeal skin is damaged and congested, with round holes; the abdomen is swollen, the anus is red and swollen, and turned outward; the head is congested, the dorsal fin is swollen, the base of the pectoral and pelvic fins is congested, the fin rays are ulcerated, and even the abdomen is longitudinally cracked from the pectoral fin to the pelvic fin, and bile leaks out. A large amount of blood or yellow jelly accumulates in the abdominal cavity, there is no food in the stomach and intestines, the stomach is pale, the intestines are filled with yellow jelly, the liver is earthy yellow, the spleen is necrotic, and there are moldy black spots on the kidneys.

(3) Harm and prevalence The disease is most harmful during the seedling and adult fish breeding period. Sometimes, some sick fish can be seen spinning in the water and dying soon after. It is especially prevalent during the seedling breeding process, with a mortality rate of up to 80%. It breaks out in the hot season, comes violently, and spreads quickly. When the water temperature is 25-30℃, a large number of sick fish will die.

(4) Prevention and control methods

① Pay close attention to water quality, maintain good pond environment conditions, keep the dissolved oxygen content in the pond water above 5mg/L, and replace one-half of the pond water.

② Appropriately reduce the stocking density of fish fry.

③ Disinfect water with 0.25-0.3g/m³ of strong chlorine, once a day for three consecutive days.

④ Add 0.6-0.7g of tetracycline per kg of dry feed, once a day for 3 consecutive days.

⑤ When feeding fish paste, add 1% salt to the feed at a fixed point every day.

2. Enteritis

(1) Pathogen: Bacillus punctatus

(2) Symptoms: The abdomen of the diseased fish is swollen, the anus is red and swollen, and yellow mucus flows out of the anus when the abdomen is gently pressed. The diseased fish swims alone. When the fish abdomen is opened, the esophagus and foregut are congested and inflamed in mild cases, and the whole intestine is inflamed and lightly red in severe cases, and the intestinal tract is filled with blood. This can occur in both fingerlings and adult fish.

(3) Hazards and prevalence: Enteritis mainly harms fish species and salted fish. The disease may be directly transmitted by fish. Therefore, the disease can be spread by mixing sick fish with healthy fish. Since the bacteria can survive in pond mud, infection may also come from the mud. In addition, zooplankton and water earthworms consumed by the fish, as well as fish paste in artificial compound feed, may also carry the bacteria.

(4) Prevention and control methods:

① The pond must be cleaned and disinfected thoroughly, and the fish should be bathed and disinfected with 2-3% salt solution before being put into the pond.

② Do not feed moldy or rotten feed. Active animals should be disinfected with 2-3% salt solution, and 1% salt should be added to the mixed feed regularly; or 0.1% fresh garlic juice should be added.

③Spray 1ppm bleaching powder in the whole pond, feed sulfaguanidine bait, use 10g of bait for every 100kg of fish on the first day, and half of it on the second day. Use it for 6 consecutive days as a course of treatment; or mix 0.3-0.4g of furazolidone per kg of feed in the feed for 2-3 consecutive days; or add 40-100g of oxytetracycline feed powder to every 100kg of feed for 5-7 consecutive days.

3. Saprolegniasis

(1) Pathogen: Saprolegnia

(2) Symptoms: When Saprolegnia first parasitizes, the naked eye cannot see any abnormality. When the naked eye can see it, the hyphae have already invaded the wound and grown inward and outward. It spreads and looks like grayish-white cotton wool. The sick fish swim abnormally and become restless until their muscles rot, they lose their appetite, become emaciated and die. The fish eggs are covered with hyphae and become white fluffy balls. The moldy eggs have become dead fish eggs.

(3) Harm and epidemic: It seriously harms hatching fish eggs and fish fry and adult fish with wounds on their body surface. This disease is most likely to occur in early spring and winter.

(4) Prevention and control methods

① Using quicklime to clean and disinfect the pond can reduce the occurrence of this disease.

②During the process of fishing, transportation and stocking, try to avoid fish injuries and control the reasonable stocking density.

③ Apply 1% malachite green ointment or an appropriate amount of iodine ammine ointment to the injured fish body.

④ Use malachite green to soak the diseased fish. Use 4-5 mg/L for big fish and 2 mg/L for small fish. Pay attention to the soaking time.

⑤ For the hatching fish eggs, you can use 7mg/L malachite green to disinfect them for 8-10 minutes for 2 consecutive days, and then sprinkle them on the water surface near the fish egg hatching rack once every morning and evening. The amount of medicine should be such that the pond water is light green until the fry are hatched. When hatching with debonded running water, add malachite once every 6-8 hours to reach 0.5mg/L, which can effectively inhibit the infection of water mold.

4. Ichthyophthirius

(1) Pathogen Ichthyophthirius multifida

(2) Symptoms: On the skin, fins, and gills of the diseased fish, small white dot-like cysts can be seen with the naked eye. In severe cases, the body surface seems to be covered with a layer of white film. The diseased fish reacts slowly or floats on the water surface. Due to bacterial infection at the lesion, the fish's body surface becomes inflamed. There may be local necrosis, scale shedding, fin rot, gill epithelial hyperplasia, and gill lamellae destruction. If the worm invades the cornea, it can cause inflammation and blindness. Eventually, the fish dies of movement disorders and breathing difficulties. Yellow catfish is susceptible to Ichthyophthirius spp., and often suffers from explosive deaths after the disease occurs. The suitable water temperature for the reproduction of Ichthyophthirius spp. is 15-25℃, pH 6.5-8.0. It rarely occurs in summer. Fish are particularly susceptible to Ichthyophthirius spp. when they are overcrowded, when there is insufficient bait, and when the fish are thin.

(3) Prevention and treatment methods

① Production measures such as pond cleaning with quicklime, fish disinfection, and reasonable stocking can prevent the spread of Ichthyophthirius.

② Soak the sick fish in 60-80 mg/L formalin for 10-18 minutes (depending on the water temperature), soak again every other day, and transfer to another pond for breeding. Thoroughly disinfect the original pond with formalin. This method is only effective in the early stage of the disease. If it is discovered too late, the sick fish will be covered with small white spots. Even if the drug is used continuously, the loss of seedlings will be great. It should be pointed out here that yellow catfish is very sensitive to mercurous nitrate, so the dosage must be accurate. The soaking time of sick fish must also be strictly controlled, otherwise it is easy to cause drug damage.

5. Trichodinasis and trichodinasis

(1) Pathogens include carp mitochondria and trichodina, and complications are common.

(2) Symptoms The gills and skin of the fish are parasitized by a large number of worms, causing disease. Yellow catfish fry often suffer from this disease, and adult fish and parent fish are sometimes infected. Oblique tube worms like to parasitize on the edges or gaps of yellow catfish, and also invade the skin of the body surface, stimulating the host to secrete a large amount of mucus, forming a pale or light blue mucus and liquid layer on the surface, and the sick fish leave the group. They lie upside down on the water surface or on their side with their heads down and their tails up, having difficulty breathing and dying soon. The wheelworms parasitizing on the body surface are larger, while the wheelworms parasitizing on the gills are generally smaller. When seriously infected, the sick fish swim wildly along the edge of the pond, showing a "horse race" phenomenon, and sometimes a layer of white lines appears on the body surface: Wheelworm disease is most likely to occur in small areas, shallow water, poor water quality, high stocking density, insufficient feed, continuous rain, and water temperature of 18-28℃.

(3) Prevention and control methods

① Thoroughly clean and disinfect the pond with quicklime.

② Soak the fish body in 1-2 mg/L copper sulfate solution, and pay attention to the soaking time according to the water temperature.

③Spray 0.4-0.5 mg/L of copper sulfate and ferrous sulfate mixture all over the area, which has a better therapeutic effect.

In addition, yellow catfish is a bottom fish, and the leftover bait and fish feces can easily accumulate at the bottom of the pond, causing the fish skin to have more mucus, leading to fish diseases and affecting fish breathing, leading to death. During the peak breeding and feeding period, it is also necessary to use 25kg/mu of quicklime slurry to sprinkle the entire pond or drain the bottom water and flush new water to improve the bottom and water quality.

------------------------------------------------------------------------------------------------------------------

The scientific name of the fish is Pelteobagrus fulvidraco.

1. Breeding methods:

1. Pond selection, cleaning and disinfection

Choose a fish pond with good water quality and sufficient water source, with a water depth of more than 1.5m and an area of ​​2-10 mu. For ponds with more than 10cm of silt at the bottom of the pond, the excess silt must be removed. After removing the excess silt, do not add water immediately, but expose it to the sun for several days before cleaning and disinfecting. 10-15 days before stocking, dissolve 50-75 kg of quicklime or 7-10 kg of bleaching powder per mu and sprinkle it throughout the pond.

2. Fish stocking and species matching

The stocking time of fish is generally chosen in winter or early spring. The stocking size is generally above 20 grams per fish, and the stocking density is generally 2000-3000 fish per mu. Before stocking, the fish should be soaked in 3-5% salt water for 10-15 minutes before stocking. At the same time, the summer fish with silver carp is sold at 1000 silver carp per mu and 3000 bighead carp per mu.

Type

3. Bait preparation and feeding

Yellow catfish is mainly carnivorous. If conditions permit, you can directly mince small fish, shrimp, snails, clams, livestock and poultry waste and other animal baits, use 3-8% flour as a binder, stir thoroughly, and feed them on the feed table. When the above animal raw materials are scarce, you can make pellet feed according to the formula of 30% fish meal, 30% bean cake, 20% bran, 10% corn, 6% flour and 4% fish oil and minerals. You can also buy full-price yellow catfish compound feed from professional manufacturers for feeding. Feeding adopts the "four fixed" principle, feeds twice a day, and the daily feeding rate is controlled between 5-8%, which can be flexibly controlled depending on the fish's feeding, weather, water temperature and other conditions.

4. Daily management and disease prevention

It is very important to regulate the water quality for yellow catfish. Starting from May, new water should be added every 10-15 days, with 10-15cm of water added each time. If the water quality is found to be too rich, some old water should be discharged in time and new water should be added to ensure that the fish have a strong feeding and normal growth. Patrol the pond every day, manage the feeding table and food, check the fish and keep fish farming records. At the same time, disease prevention and control work should be carried out in accordance with the principle of "prevention first, prevention and control combined". During the epidemic season of fish diseases, 1ppm bleaching powder or 25

ppm quicklime. During daily pond inspections, pay attention to the activities of the fish, detect the disease early, treat it in time, and prevent the disease from spreading. Yellow catfish is a scaleless fish and is more sensitive to drugs. Trichlorfon, copper sulfate and other drugs should be used with caution.

II. Introduction:

The garfish likes to live in still water or slow currents, living in groups at the bottom. It has a strong ability to adapt to the environment and likes to move and feed under weak light conditions. The water temperature for survival is 4-38℃, and the best water temperature for growth is around 25℃. No special heat preservation and heatstroke prevention measures are required in winter and summer. The optimal pH value is 7.0-8.4. The growth rate of this species in the pond is average. It can be put on the market after two years of cultivation. The commercial fish weigh 100-200 grams.

Pelteobagrus fulvidraco is a bottom-dwelling economic fish that is widely distributed in my country's freshwater bodies and is farmed on a large scale in ponds.

The artificial breeding of yellow catfish is a new breeding technology developed in recent years. The following are the technologies of breeding, seedling cultivation, pond breeding and cage breeding:

1. Reproduction and seedling cultivation technology

1. Selection and cultivation: Select two-year-old wild yellow catfish with smooth body surface, complete fins, no disease or injury and weighing 75-100 grams for females and 125-150 grams for males as parents, and place them in ponds for special pond cultivation at a ratio of 1:1.2 between males and females.

2. Artificial Bi Huan Cong induction of spawning: Before induction of spawning, females with swollen and soft abdomens should be selected, and a small amount of eggs should flow out when the abdomen is gently pressed; males should be selected as broodstock with swollen abdomens, and semen should flow out and spread rapidly in the water when squeezed by hand. The broodstock for induced spawning can adopt the breeding facilities of the four major carps. Since yellow catfish has the habit of digging holes to protect eggs, the fish nest must be placed at the bottom of the spawning pond when setting up the fish nest, and the fish nest should be tied tightly to prevent the broodstock from destroying the fish nest when estrus and spawning. The male and female broodstock for induced spawning are matched in a 1:1 ratio, and the induced spawning drugs are generally ovulation hormone 2 (LRH-A2), human chorionic gonadotropin (HCG), dioconazole or their mixed preparations. After induced spawning, put them in the spawning pond and let them spawn naturally.

3. Artificial hatching: Yellow catfish is a fish that lays eggs in batches. The spawning period is relatively long, generally lasting more than 6 hours. The fish nest should be moved into the hatching ring or hatching tank for hatching only after most of the parent fish have laid eggs. Since the eggs of yellow catfish are attached to the fish nest, it is only necessary to keep the water flowing slightly during hatching. The fish nest with the eggs can also be placed in a still water pool or a net cage for hatching. When hatching in still water, oxygen-enhancing equipment should be arranged.

4. Fry cultivation: When the water temperature is 25℃, the fertilized eggs will hatch two days after hatching, and the fry will begin to eat on the third day after hatching. The first food they eat is small zooplankton. At this time, the fry must be transferred to the fry cultivation pond for transfer cultivation. Before the transfer, the first food for the fry should be cultivated in advance, and artificial feed such as egg yolk and fish paste should be added. In the early stage of fry cultivation (before 1.5cm), the main food is cultivated natural bait. When the fry grows to 1.5cm, it is necessary to start feeding, and add some compound feed every day until the fry completely eats the compound feed. When the fry grows to more than 3cm, the next stage of cultivation can be carried out.

2. Pond culture technology

1. Pond selection, cleaning and disinfection: Choose a fish pond with good water quality and sufficient water source, with a water depth of more than 1.5m and an area of ​​2-10 mu. For ponds with more than 10cm of silt at the bottom of the pond, the excess silt must be removed. After removing the excess silt, do not add water immediately, but expose it to the sun for several days before cleaning and disinfection. 10-15 days before stocking, dissolve 50-75 kg of raw stone ash or 7-10 kg of bleaching powder per mu into a slurry and sprinkle it throughout the pond.

2. Fish stocking and species matching: Fish stocking is generally carried out in winter or early spring, with a stocking specification of more than 20 grams per fish and a stocking density of 2,000-3,000 fish per mu. Before stocking, fish should be soaked in 3-5% salt water for 10-15 minutes before stocking. At the same time, silver carp and silver carp are matched with summer fish, with 1,000 silver carp per mu and 3,000 bighead carp per mu.

3. Preparation and feeding of bait: Yellow catfish is mainly carnivorous. If conditions permit, you can directly crush small fish, shrimp, snail and clam meat, livestock and poultry foot feed and other animal baits, use 3-8% flour as a binder, stir well, and place it on the feed table for feeding. When the above-mentioned animal raw materials are lacking, you can make pelleted feed according to the formula of fish meal 30%, bean cake 30%, bran 20%, corn 10%, flour 6% and 4% of flour to feed. You can also buy full-price yellow catfish combined with feed from professional manufacturers for feeding. The "four fixed" principle is adopted. The daily bait is given twice a day, and the daily bait rate is controlled between 5-8%. According to the feeding of fish, weather, water temperature, etc.

4. Daily management and disease prevention and control: It is very important to adjust the water quality of yellow catfish. Starting from May, fresh water should be added every 10-15 days, each time 10-15 cm. If the water quality is found to be too fat, some old water should be discharged in time and fresh water should be added to ensure that the fish are in full food and grow normally. Perform the pond patrol observation every day, manage the food table and food, check the fish body and keep a good record of fish raising. At the same time, disease prevention and control work should be carried out in accordance with the principle of "prevention as the main and prevention and control". During the epidemic season of fish disease, 1 ppm bleach or 25 ppm quicklime should be sprinkled in the pond every 10-15 days. When patroling daily, pay attention to observing the fish's activities, detect the condition early, treat and deal with it in time to prevent the spread of the disease. Yellow catfish is a scaleless fish and is more sensitive to drugs. Dibaizeng, copper sulfate and other drugs should be used with caution.

3. Cage breeding technology

1. Selection of water areas: Choose water areas such as leeward and sunny, and water depths of more than 4 meters to place cages.

2. Production and installation of cages: 3×3 polyethylene junction mesh is used, with specifications of 3m long, 3m wide, 1.6m deep or 4m long, 4m wide and 1.6m deep; the outer mesh is 3cm and the inner mesh is 1cm. The cage is made of bamboo as a float rack, and the anchor rope fixing method is used to form a "one" or "公" font.

3. Free stocking of fish species: The stocking density of 25g of tail weight is 100 tail/m2, and the stocking density of 50g of tail weight is 70 tail/m2. When the fish species enter the box, soak in 3-5% saline solution for 10-15 minutes.

4. Feeding management: The daily feeding amount is 5-8% of the fish's weight. The specific amount should be flexibly controlled depending on the weather, water temperature, and the fish's activity. The number of feeding baits is twice a day, that is, once in the morning and once in the evening. The amount of feeding each time should be eaten within 1 hour. According to the habit of yellow croaker's night foraging, the feeding amount should account for 60% in the evening and the feeding amount in the morning. The feeding of baits should follow the "four determinations" principle.

5. Daily management: Wash it every 7-10 days and clean the feed table once a day. To prevent fish from escaping from breaking the box, you should carefully observe and check whether the net clothes are damaged or slippery. If there is any, repair it in time. In order to allow the yellow fish to eat normally, the net should be covered with a sunshade net.

6. Disease prevention and control: Yellow catfish suffers less and suffers a lot of losses once the disease occurs. Therefore, prevention should be the main focus during cage breeding. The feed table should be disinfected once a day and sprinkle quicklime water in the cage regularly.

Yellow catfish is a scaleless fish and is more sensitive to drugs such as zombies and copper sulfate, so it should be used with caution.

{Please do not copy, otherwise complain}