CATDOLL : CATDOLL: Will catfish eat dead shrimp?

Will catfish eat dead shrimp?

Catfish are omnivorous fish and will eat many rotten things, so catfish will also eat dead shrimps!

Local catfish breeding technology

Catfish, scientifically known as catfish, commonly known as catfish, is one of the popular aquatic products among the general public because of its special medicinal value and delicious taste.

1. Biological characteristics of catfish

Catfish is an omnivorous fish that prefers shade and is afraid of sunlight. It lives in groups and lives on the bottom. It mainly feeds on animal feed. In natural waters, it often feeds on small fish, shrimp, insects and other animal carcasses in the water. However, artificial breeding uses water earthworms, cladocerans or silkworm pupae, slaughterhouse scraps, etc. It can also be fed with artificial feed made from fish meal, peanut bran, corn flour, etc.

2. Catfish breeding

1. Fish pond requirements. The pond foundation must be solid, check and block the holes, and the inlet and outlet must be separate to prevent the pond water from overflowing the top (over the foundation) during the rainy season and causing catfish to escape with the water.

2. Disinfection of fish ponds. Before stocking fry, the fish pond must be completely cleared of debris and mud at the bottom of the pond. Use 25 kg of quicklime or 20 kg of tea seed bran or 5 kg of bleaching powder per mu to spray the entire pond for disinfection. After a week, the water is tested to confirm safety before stocking fry.

3. Fish fry release. Catfish breeding can be divided into two methods: mixed breeding and pure breeding. Mixed breeding means that in the "four major carp" pond, 150-200 "five-finger fish" (that is, about 200 per kilogram) are mixed and raised per mu. Usually, no special feed is needed, and 15-25 kilograms of catfish can be harvested per mu; pure breeding is to use a fish pond with a solid foundation, convenient drainage and irrigation, and a water depth of about 1.5 meters. The area is generally 4-6 mu. 3 cm seedlings are released per mu, 10,000-15,000. In the early stage of stocking, a small water body of 5-8 square meters is enclosed by dense mesh at the edge of the pond. It is first cultivated in shallow water for 10-15 days. As the fry grow, the water level is deepened day by day, and finally the mesh is pulled open to allow them to grow on the large water surface.

4. Daily management. After the fry are released, the pond should be patrolled in the morning and evening to observe the growth of catfish. Feeding should adhere to the "four fixed" principle, and the feeding amount should be 8%-10% of the fish's body weight. However, some people increase or decrease the feeding amount based on whether the fish have finished eating, and try to avoid waste after eating. Be prepared for the "four preventions" (i.e., prevention of sudden cold and heat, prevention of escape, prevention of enemies, and prevention of fish diseases). When using ponds to raise catfish, through scientific management, the survival rate can be guaranteed to be above 45%-55%. After 3-4 months of breeding, 350-500 kg of commercial fish can be harvested per mu. When the supply of seedlings is guaranteed, two crops can be raised in a year.

3. Disease prevention and control of catfish

In the process of mixed culture of catfish and fish, the probability of disease is low due to the low density, but in high-density pure culture production, various diseases may occur at any time from seedling to harvest. Therefore, in the process of pure culture, disease prevention is particularly important. In daily management, fish bodies must be disinfected when fry are released. Commonly used salt is diluted with water at a ratio of 1:30, that is, 1 kg of salt is used with 30 kg of water. The fry before being put into the pond should be soaked for 20 minutes before the fry can be put into the pond. When the fry are put into the pond, the transported fry will have "spasmodic waist" symptoms (commonly known as "hard body") due to the large difference in pond water temperature. Before the fry are put into the pond, the pond water must be slowly flushed into the bucket for transporting the fry with a bucket to slowly balance the water temperature before the fry can be put into the pond.

After the fry are put into the pond, the feed they are fed is different from the feed they used for raising the fry. Intestinal diseases often occur within a few days of stocking, causing a large number of fish deaths. Therefore, from the first feeding after stocking, 6-10 grams of erythromycin should be mixed with 1 kg of feed and fed once a day for five consecutive days.

The most harmful disease in the catfish breeding process is viral skin rot. This disease usually occurs when the fish weigh about 1 liang, one month after the fry are released. Blisters appear on the body surface of the diseased fish, the base of the fins is congested and rotten, and in severe cases, the whole body ulcers appear. At this time, a large number of dead fish will appear until the whole army is destroyed. Therefore, it is necessary to regularly sprinkle the whole pond with quicklime and water, using 10-15 kilograms of lime per mu, and use it for 15 consecutive days. If this disease occurs, most of the time it cannot be controlled. This disease can only be managed regularly with medication and prevention.

Catfish farming is difficult to control

In spring (March to May in the Gregorian calendar), the temperature gradually rises, generally between 10 and 20 degrees Celsius, and the water temperature environment is more suitable for the growth and reproduction of various pathogens, especially April to May is the peak season for fish diseases - barley yellow. When the fry are hatched in early spring, the fish eggs are susceptible to Saprolegniasis; the fry are mainly susceptible to wheelworms, Ichthyophthirius, Dactylopius, Diplostomum, fish lice and other fish diseases; in spring, adult fish are susceptible to microbial fish diseases, such as viral hemorrhagic disease, enteritis, gill rot, printing disease, and silver carp iodine spore disease.

In summer (June to August in the Gregorian calendar), the temperature is generally between 26 and 28 degrees Celsius, and fish diseases are slightly less common than in spring. At this time, fish species gradually grow up and their disease resistance is enhanced. Therefore, ciliate and flagellate fish diseases gradually decrease. In addition, according to surveys, microbial fish diseases in spring continue to exist in summer, including gill rot, hemorrhage, red skin, enteritis, and printing disease. At this time, anchor fish disease is more common among parasites. In midsummer, high-yield ponds are often prone to flooding.

In autumn (September to October in the Gregorian calendar), the temperature gradually drops, and the temperature is generally between 23 and 15 degrees Celsius. The water temperature environment is basically similar to that in spring, especially August to September is the peak season for fish disease - "Bai Lu Xin". Summer fish species mainly suffer from wheelworms, Ichthyophthirius, Dactylopius, complex trematodes, fish lice and other fish diseases. In autumn, large-sized fish are prone to microbial fish diseases, such as viral hemorrhagic disease, enteritis, gill rot and other diseases.

In winter (December to February in the Gregorian calendar), the temperature is relatively low, generally between 3-6 degrees Celsius, and fish diseases are rare. Winter is the period for stocking fish, and fish bodies are often scratched by netting or transportation, and Saprolegniasis may also occur; when the water temperature is high, it is possible to develop tricholoma and Ichthyophthirius; when the water temperature of overwintering fish is below 10 degrees Celsius, the temperature difference between the air temperature and the water temperature in the wintering room is too large, and the fish will float to the surface due to lack of oxygen, causing frostbite on the top of the head.

There are 12 common fish diseases that can be caused by the change of temperature in spring, summer, autumn and winter. Among them, there are 7 main parasitic diseases: trichodinasis, Ichthyophthirius, Dactylopius, anchorhead mycidiella, fish lice, silver carp iodine spore disease, and Chinese mycidiella; there are 5 main microbial diseases: hemorrhagic disease (red skin disease), enteritis, gill rot, printing disease, and saprolegniasis. As the saying goes, "If you don't raise fish plague, you will be rich." In fish farming, once fish diseases occur, mild cases will affect the growth and development of fish, and severe cases will cause the death of some fish. Therefore, it is necessary to attach importance to the prevention and control of fish diseases and actively implement the policy of "early prevention when there is no disease and early treatment when there is disease."

The female anchorhead worm's head drills into the host's muscles, causing tissue damage, inflammation, and ulcer formation. Sick fish become restless, have a loss of appetite, become emaciated, and swim slowly. Fish of 6-10 cm in size may become deformed and lose balance. The worms exposed outside the fish's body are often attached with protozoa such as nematodes, algae, and molds. When seriously infected, the fish's body looks like it is covered with a straw raincoat, which increases the burden on the fish and affects the sick fish's ability to move. When there are a large number of worms parasitizing in the fish's mouth, the sick fish's mouth cannot be closed, and it cannot eat and dies. Fish with smaller scales, such as silver carp and bighead carp, will develop pomegranate-like erythema on their skin due to the redness, swelling, and inflammation of the surrounding tissues caused by the parasitism of anchorhead worms. When the anchorhead parasite parasitizes fish with larger scales such as grass carp and carp, the scales of the parasitic area will be eaten away and become notched, the scales will become lighter in color, and congested erythema will appear at the parasitic area, but the swelling is generally not obvious.

Before stocking the fish, check and if any anchorhead parasites are found, remove them first and then soak them in potassium permanganate before stocking.

[Treatment Method]

It can be seen with the naked eye, and can be removed with tweezers, and then the wound can be smeared with red medicine! (

Fish lice are parasitic crustaceans that live on goldfish most of the time. They only move in the water when they are larvae and adults and lay eggs. There are two suckers on the ventral side of fish lice, which are used to attach to the body of goldfish. The mouth is needle-shaped, which is used to pierce the fish body and suck blood, causing the affected area to bleed and turn red, making it susceptible to bacterial infection. Unless goldfish are attacked by a large number of fish lice, they are unlikely to die from this disease. Organophosphorus insecticides are specific medicines for fish lice, but they are also harmful to goldfish. The best way is to remove the fish lice one by one with sharp pliers, or treat them with trichlorfon, Sera fish pond deworming agent, American deworming agent, American deworming special tablets, Queen Whale deworming agent, and AZ00 deworming agent.

Check fish before stocking

Bacterial tail and fin rot: Tail and fin rot caused by bacteria is highly contagious, starting from the fin rays, then the body rots and eventually the fish dies. There are two symptoms of this fin rot. The first is that the rot starts from the edge of the fin and then spreads inwards, and the second is that the rot starts from the center of the fin and spreads in all directions. The affected area turns white and finally falls off. Fish are most susceptible to this disease when their body resistance is weakened after transportation or spawning. Once the diseased fish is found, they must be isolated immediately and treated with antibiotics or drugs such as chloranil. When the symptoms of fin rot appear slowly, the treatment method is to replace part of the tank water, clean the filter, add a little salt to the tank, and stop feeding for a few days. The role of salt therapy is to increase the specific gravity of the water, change the osmotic pressure in the water, and kill bacteria and other pathogens through changes in osmosis.

Saprolegniasis is also known as white hair disease. Fish are very susceptible to Saprolegniasis due to careless handling and excessive stocking density in wintering fish ponds. The pathogens are Saprolegnia and Corythuja. The hyphae are slender and branched. One end of them is root-like and grows inside the fish's skin, while the rest is exposed outside the body. The hyphae are up to 3 cm long, grayish white, and soft like cotton wool. In the early stage of the disease, the mucus on the surface of the fish increases, forming a layer of white film. In the late stage of the disease, the hyphae penetrate deep into the skin, and the mortality rate is very high.

[Prevention and treatment methods]

You can choose 0.03 grams of malachite green or methylene blue, dissolve it in 10 kilograms of water, soak the sick fish for 3-5 minutes, rinse it with clean water, and put it in the aquarium. It takes multiple applications to recover.

Perforation: The characteristic pathological changes of diseased fish are mainly manifested on the body surface of the diseased fish, characterized by the initial erythema, followed by skin and muscle necrosis and ulceration, ulceration and perforation. The sites of occurrence can be on the chest, abdomen and both sides of the tail, the back of the head, the base of the fins, etc., and are most common on both sides of the body. There are 1-2 lesions on a sick fish, and as many as 7-8. Initially, a soybean-sized erythema appears on the body surface. This erythema gradually expands, and the skin at the erythema is red and swollen, the scales are loose, and the base is congested. Subsequently, the epidermis erodes, the scales fall off, and the congested and hemorrhagic dermis is exposed. Then the dermis also necrotizes and ulcerates to expose the muscles. After the muscles ulcerate, pit-shaped ulcers are left. The size and depth of the ulcers are different. The small ones are 0.2-0.3×0.2-0.5 cm, and the large ones can reach 2~5×2~6 cm. The depth of shallow ulcers is only about 0.1 cm, and the deep ones can reach 0.6 cm. Due to the different degrees of tissue necrosis in the ulcer, the ulcer surface is uneven. The shape of the ulcer is quasi-circular, oval or irregular with uneven edges. There are irregular bleeding areas in the ulcer. Saprolegnias are parasitic in some old ulcers. The tissues around the ulcer are congested, red, swollen, and the scales stand up. Ulcers that have already formed will eventually develop into perforations. The muscles will completely necrotize and rot, penetrate the body wall, form perforations, expose the body cavity and internal organs, and water will quickly flow into the body cavity, causing the death of the sick fish. The shape of the perforations is mostly quasi-circular. The diameter of small perforations is 1 to 2 cm, and the large ones are 2-4 cm. There is usually only one perforation on a fish, and residual bone spurs can be seen at the perforation. Ulcers occurring in the tail will rot until the bones are exposed. Some sick fish can be seen with protruding eyeballs. In cases with more serious changes in the body surface, it can be seen that the liver, spleen, kidneys and other internal organs are congested, swollen, and fragile, and there is a lot of mucus on the gill filaments and intestinal mucosa.

[Prevention and treatment methods]

1. Before the fish are put into the box or put into the pond, disinfect the fish body by soaking it in 10ppm bleaching powder or 20ppm potassium permanganate for 10-15 minutes.

2. Avoid damaging the fish body during operation.

Soaking medicine:

(1) Salt: Add 1.5 kg of salt to every 50 kg of water and soak for 5 minutes.

(2) Potassium permanganate: 20ppm, soak for 10-15 minutes.

(3) Furazolidone: Use 0.3 grams per cubic meter of water and soak for 1-2 hours.

Apply the medicine:

(1) Apply tetracycline or chloramphenicol anti-inflammatory ointment to the affected area of ​​the fish.

(2) Mix furazolidone or furazolidone with vaseline and apply to the affected area of ​​the fish.

Spinal curvature in young fish is often caused by parasites or genetic defects (it may also be caused by drug poisoning, such as excessive doses of trichlorfon), while for large fish the main cause is damage to the nervous system.

White spot disease is also known as Ichthyophthirius punctatus. The pathogen is a ciliate called Ichthyophthirius punctatus. Its body is spherical or oval, with short and evenly distributed ciliates on the surface. There is a large horseshoe-shaped nucleus in the center of the body. The vesicles on the diseased fish are caused by the dense parasitism of these Ichthyophthirius punctatus. This is a common disease of goldfish and tropical fish. In the later stage of the disease, the surface of the fish will be covered with a layer of white film, the mucus on the body surface increases, the body color becomes dull, the luster decreases, the fish becomes thin, swims slowly, and is listless. Sometimes it floats on the water surface, and sometimes gathers in a corner of the fish tank. It rarely moves and eventually dies in large numbers.

[Treatment Method]

The fish can be immersed in a solution containing 1 tablet of 50 mg of furazolidone per kilogram of water for one week; or immersed in a solution of 1 to 3 parts per million of mercurous acetate for 30 minutes, or the temperature can be slightly increased. The original water in the fish tank should be completely replaced.

Gill rot

Gill rot is mostly caused by parasitic infestation or bacterial infection, so there are two types of gill rot: parasitic gill rot and bacterial gill rot.

(1) Parasitic gill rot: The pathogens are ringworms or wheelworms. They infect each other, causing obvious swelling of the gills and difficulty in opening the gill covers. In severe cases, the gill filaments are partially ulcerated, exposing the gill cartilage, making it difficult for the fish to breathe and eventually die. Prevention and control methods: 0.5-0.8 grams of crystal trichlorfon can be used, put in 10 kilograms of water, and soak the diseased fish for 10-15 minutes. You can also use 0.2 grams of crystal trichlorfon, 0.2 grams of copper sulfate, and 0.2 grams of iron sulfite, mix them in 10 kilograms of water, and soak the diseased fish for 10-15 minutes. Or you can use 0.2-0.3 grams of crystal trichlorfon dissolved in water, sprinkle it in 1 ton of feed water, and use the medicine 1-2 times a week to effectively kill parasites in the water.

(2) Bacterial gill rot: The pathogen is Saprolegnia, and the gill filaments of the diseased fish lose blood severely, turn white, and in severe cases, there are flocculent hyphae adhering, and the mortality rate is extremely high. Prevention and control methods: You can choose to use 50 grams of salt and 50 grams of baking soda, mix them in 10 kilograms of water, and soak the diseased fish for 15-20 minutes. You can also use 0.7 grams of malachite green, put it in 100 grams of water, and soak the diseased fish for 15-30 minutes.

(3) Myxosporean gill rot: The pathogen is myxosporean. Many grayish-white spots or cysts visible to the naked eye will appear on the gill filaments, which will grow from small to large and damage the fish gills. Once the cysts rupture, countless spores enter the feed water and re-invade the gills of healthy fish. The gill filaments lose blood and cause large-scale death. Gill rot caused by myxosporean is relatively rare. Prevention and control methods: Use the juice soaked in the bark of three-year-old maple poplar, absorb an appropriate amount, put it in 10 kilograms of water, soak the diseased fish for 5-10 minutes, and use it repeatedly to see the effect. You can also use 150 grams of ammonia water, put it in 10 kilograms of water, soak the diseased fish for 5-10 minutes, and use it repeatedly to see the effect.

(4) Myxococcus gill rot: The pathogen is myxococcus. The gill filaments of diseased fish are ulcerated and covered with a lot of white mucus. In severe cases, the gill filaments are corroded into small holes, the cartilage is exposed, and the mortality rate is very high. Prevention and control methods: 1-2 grams of furazolidone can be used, dissolved in 10 kilograms of water, and the diseased fish can be soaked for 15-20 minutes. High-concentration salt water can also be used to soak the diseased fish for 15-20 minutes. You can also use 11.5% concentration of chloramine 0.05 grams and 0.2 grams of furazolidin, mix them and put them in 10 kilograms of water. Multiple use of the medicine has a good effect.

Spring is a season when fish diseases are common. In order to make it easier for fish lovers to identify and prevent them, the above Word document is a simple table of common fish diseases, common drugs and precautions for naked eye identification.

1. Nitrofurazone (C6H6O4N4)

Furacilin is also known as furanosin. It is a lemon yellow crystalline powder, odorless, bitter, and only slightly soluble in water. It has a strong killing power against Gram-negative bacteria, and bacteria do not develop drug resistance to this drug. It is a commonly used drug for the treatment of bacterial diseases.

2. Copper sulfate (CUSO4*5H2O)

Copper sulfate, also known as blue vitriol and gall vitriol, contains 5 molecules of crystal water. It is a transparent dark blue crystal or powder. It loses water in the air and turns white. It can turn blue again after absorbing moisture. If it is too humid, it can also deliquesce, but it does not affect the efficacy. Copper sulfate is easily soluble in water. The aqueous solution is weakly acidic, has astringent effect and strong ability to kill pathogens. The size of its sterilization ability is often affected by various factors in the water. Therefore, the dosage needs to be flexibly controlled according to the specific situation. It is generally believed that the more organic matter in the pool water, the lower the water temperature, and the higher the pH value, the less toxic the copper sulfate is, and the greater the safe concentration. The higher the water temperature, the lower the pH value, and the less organic matter, the greater the toxicity of copper sulfate and the lower the safe concentration.

Copper sulfate can kill a variety of protozoa and fleas that parasitize the fish, and is a commonly used topical drug. However, it cannot be used frequently because of its residual toxicity (copper can remain in the gills, muscles, liver, and kidney tissues of fish) and affects the fish's feeding and growth. In addition, the safe concentration range of copper sulfate is relatively small, and the water body should be accurately measured when used. The temperature of the water in which copper sulfate is dissolved should not exceed 60°C, otherwise it will easily become ineffective.

3. Ferrous sulfate (FESO4*7H2O)

Also known as green vitriol and iron vitriol, it contains 7 crystal water molecules. It is a transparent, light green crystal or powder, odorless, astringent, and easily weathered in dry air. It is easily oxidized and hydrolyzed in humid air to produce yellow-brown insoluble basic iron sulfate, which has no medicinal value. Therefore, it must be sealed and moisture-proof.

Ferrous sulfate is an auxiliary drug with astringent effect. It is mainly used to clear obstacles for copper sulfate and other drugs to kill parasites.

4. Trichlorfon (C4H8CL3O4P)

The chemical name of this drug is 0,0-dimethyl (2,2,2-trichloro-1-hydroxyethyl) phosphate, which is a highly effective and low-toxic organophosphorus insecticide widely used in agriculture, animal husbandry, sanitation, etc. It is relatively soluble in water. It is stable under acidic conditions and can be quickly decomposed into more toxic dichlorvos under alkaline conditions, and continue to decompose until it has no killing activity.

Dichlorodiphenyltrichloroethane powder can be used for fish disease prevention and control. The active ingredients are available in different specifications such as 2.5%, 4%, 25%, 50%, etc., and 90% crystals are commonly used.

Trichlorfon is an effective insecticide with low toxicity, low residue and short residual time. Its mechanism of action is that organophosphorus binds to cholinesterase, which is responsible for the normal transmission of nerve impulses, inhibits the activity of cholinesterase, and loses the ability to decompose acetylcholine. As acetylcholine accumulates in nerve cells, the nerve transmission function is stopped, leading to poisoning and death of insects and crustaceans. In the prevention and control of fish diseases, trichlorfon is widely used to prevent and control fish diseases caused by crustaceans and parasitic helminth diseases outside and inside the body of fish.

This product is purple-black elongated crystals, opaque, with a blue metallic luster, odorless, and easily soluble in water. It is a strong oxidant. When it meets organic matter, it releases oxygen and oxidizes the organic matter, thus having a strong bactericidal power, and it itself is reduced to manganese dioxide. Manganese dioxide can combine with protein to form a complex of protein salts, so it has a convergence effect at low concentrations, and a stimulating and corrosive effect at high concentrations. In the prevention and control of fish diseases, it is used to prevent and control trigeminal worm disease, ringworm disease, and anchor fish disease.

6. Sodium chloride (NACL)

In fish disease prevention and treatment, its penetration effect is used to kill some external parasites and microorganisms.

7. Cupric chloride (CUCL2)

It is a blue powder that is soluble in water. Its chemical properties are less affected by organic matter than copper sulfate. It is used to kill Lymnaea snails and prevent schistosomiasis and schistosomiasis. The dosage must be calculated accurately. A slight overdose can cause poisoning and death of fish.

8. Malachite Green (C23H25N2CL)

Also known as malachite green and benzaldehyde green, it is a lustrous emerald green crystal and belongs to the triphenylmethane dye family.

Malachite green is a kind of medicinal dye with strong antibacterial effect and is soluble in water. It is used to prevent and control fish diseases such as Saprolegniasis and Ichthyophthirius, with good results.

Malachite green is a photosensitive drug, and its toxicity increases with the increase of light intensity. Therefore, it should be noted that it should not be used during the day when the sun is strong. At the same time, the pH value of the pool water is above 9 and it will not have the desired effect. It should not come into contact with zinc or tinplate utensils to avoid acute poisoning of fish due to zinc dissolution. Malachite green should not stick to human skin, let alone enter the mouth.

Malachite green can cause mild inflammation of the gills and skin epithelial cells of fish; cause mild dilation of the renal tubular lumen and enlargement of the nuclei of the renal tubular wall cells; more importantly, it affects the enzymes in the fish intestines, reducing the secretion of the enzymes, thereby affecting the fish's feeding and growth, so it cannot be used frequently.

Abbreviated as SD. It is a white or slightly yellow crystalline powder, odorless and tasteless, insoluble in water, stable in the air, and its color gradually darkens when exposed to sunlight. It should be stored in a sealed container to avoid light. It is an oral medicine, completely absorbed, and the body excretes it slowly. The effective concentration can be maintained for a long time, and the side effects and toxicity are small. It is used to treat enteritis and red skin disease in fish disease prevention and control.

10. Furazolidone

Also known as Furazolidone. It is a yellow crystal, odorless, and extremely difficult to dissolve in water. It has a broad-spectrum antibacterial and antiprotozoal effect. It is less likely to produce drug resistance, has low toxicity, and has no side effects. It is mainly used to treat intestinal infections. Sprinkling it all over the pond can prevent and treat white head and white mouth disease and gill rot.

11. Chlortetracycline Hydrochloride

Golden yellow crystalline powder, odorless, bitter. Stable in air, easily deteriorates in light, and quickly loses effectiveness in alkaline solution. Not suitable for contact with metal, preferably refrigerated. Has a wide antibacterial spectrum, mainly inhibits bacteria, and has bactericidal effect at high concentrations. Drug-resistant individuals may develop drug resistance, but generally not high. Used in fish disease prevention and control to prevent white skin disease, rotten skin disease, etc.

12. Oxytetracycline Hydrochloride

Also known as chlortetracycline hydrochloride. Yellow crystalline powder, odorless, bitter, stable, easily soluble in water, decomposed and ineffective in alkaline conditions. The antibacterial spectrum is similar to that of chlortetracycline hydrochloride, with low toxicity. Drug resistance can also be generated, but very slowly. It is the same as chlortetracycline hydrochloride in the prevention and treatment of fish diseases.

13. Penicillin

Also known as penicillin. Penicillin salt is a light yellow powder that is easily soluble in water. It is extremely unstable and can be rapidly decomposed by heating, light, or the addition of acid or alkali. Therefore, the expiration date should be noted.

The antibacterial spectrum of penicillin is not as broad as that of sulfonamides, and it has strict selectivity against bacteria. It mainly acts on Gram-positive bacteria and some Gram-negative bacteria. It has an antibacterial effect at low concentrations and a bactericidal effect at high concentrations. In the prevention and treatment of fish diseases, it is mainly used to sprinkle in the water during the transportation of broodstock to prevent the water quality from deteriorating during transportation. It is used for intramuscular injection of post-natal broodstock to prevent bacterial infections.

14. Erythromycin

This product is a light yellow crystalline powder, odorless and bitter. It is hygroscopic in the air and difficult to dissolve in water. Erythromycin is alkaline, and its solubility in water is greatly increased after it is combined with organic acids to form salts. This product is relatively stable in a dry state and easily loses effectiveness in aqueous solution. It is unstable when exposed to acid, and its effectiveness is significantly reduced when the pH value is below 4. The aqueous solution should be refrigerated and will gradually lose effectiveness at room temperature.

Erythromycin has a stronger effect on Gram-positive bacteria than Gram-negative bacteria. Bacteria quickly develop resistance to this product, but it is not lasting. Sensitivity can be restored 3-6 months after stopping the drug. In fish disease prevention and control, it can prevent and treat white mouth disease and gill rot.

Furuncle disease: One or more pustules similar to human furuncle disease develop on the local tissue of the fish's body. The site of the disease is not fixed, usually on both sides near the base of the fish's dorsal fin.

Typical symptoms are: infection lesions form in the subcutaneous muscles. As the bacteria in the lesions multiply and the disease progresses, the muscle tissue dissolves, bleeds, exudes body fluids, and cells become free, filled with pus, blood cells, and a large number of bacteria. The affected area softens and bulges outward. It feels soft and swollen when touched. The raised skin first becomes congested, then bleeds, then necrotizes and ulcerates, forming a crater-shaped ulcer. When the affected area is cut open, the muscle dissolves and appears gray-yellow turbid or curd-like.

Histopathological sections show that the dermis of the affected area is swollen, degenerated, congested, and hemorrhagic, but not yet necrotic. The skeletal muscle fibers in the center of the lesion are completely disintegrated, and a large number of bacilli, pus, and a small number of necrotic and disintegrated inflammatory cells can be seen in it. The boundary between the lesion and the surrounding normal tissue is unclear, bacteria spread in the tissue, a large number of inflammatory cells diffusely infiltrate the interstitial space, and purulent exudate spreads along the loose interstitial space. This is a chronic suppurative inflammation among exudative inflammations, namely cellulitis.

[Diagnosis] The diagnosis can be made based on symptoms, pathological changes and epidemic situation. Some myxosporeans parasitize in muscles, which can also cause swelling on the body surface, loss of elasticity and softening of muscles in the affected area, and congestion of the skin (such as the crucian carp iodine bubble parasitizes in the back muscles behind the head of crucian carp). To distinguish between the two, it is necessary to use a microscope to examine the compression film at the center of the lesion. In the former, a large number of bacilli can be seen without myxosporeans parasitizing, while in the latter, the opposite is true.

Prevention and treatment methods:

1. Thoroughly clean and disinfect the pond;

2. Use bleaching powder to hang the basket;

3. Spray 1 mg/L of bleaching powder throughout the pool;

4. Feed fish with sulfathiazole. Use 5 grams of the drug for every 50 kg of fish on the first day, and reduce the dosage by half on the 2nd to 6th days. Mix the drug with flour and feed it for 6 consecutive days;

5. Mix 5g of furazolidone with feed for every 100kg of fish every day, feed twice a day in the morning and afternoon for 15-20 days;

6. For every 100 kg of fish, mix 5-7 g of oxytetracycline hydrochloride in feed and feed it twice a day, morning and afternoon, for 10 consecutive days.

Pine scale disease:

[Symptoms] The symptoms of the diseased fish are characterized by a rough body surface, and most of the scales at the tail are spread out like pine cones, while the scale sac at the base of the scale is edematous, and translucent or bloody exudate accumulates inside, causing the scales to stand up. When a little pressure is applied to the scales, the liquid will spray out from the scale sac, and the scales will fall off, sometimes accompanied by congestion of the fin base and skin surface, protruding eyes, and swollen abdomen. The diseased fish swims slowly, has difficulty breathing, turns sideways, and the abdomen is upward, and dies after 2 to 3 days. The disease is easy to occur when the water quality is not clean, the light is insufficient, the water is lacking oxygen, the water temperature is too high, and when the scales of the fish are scratched. Goldfish and koi often suffer from this disease, which is more prevalent in spring every year. Among tropical ornamental fish, foam-oviparous fish such as the Percichthyidae, Bettas, and Gnaphalidae often suffer from this disease. This disease is difficult to cure. Even after recovery, the color, luster, and body shape are not as good as before.

[Treatment method] The sick fish can be immersed in a tetracycline solution with a concentration of 1/50,000 unit for 1 hour, or bathed in a mixture of 3% sodium chloride solution and 1% sodium bicarbonate solution for 10 minutes; or immersed in chloramphenicol solution, or furazolidone powder plus sulfamethoxazole solution, or gentamicin solution. 1% of the above-mentioned liquids can be diluted into a low dose for spraying, and the effect can be seen after several days of persistence.

Printing Disease

The disease is caused by Aeromonas punctata subspecies punctata. The bacteria are short rod-shaped, with round ends, most of which are connected to each other, and a few are single. The bacteria are 0.7-1.7 microns long and 0.6-0.7 microns wide. They are motile, have a single flagellum at the extreme, and have no spores. They are evenly stained and are Gram-negative.

The lesions mainly occur in the trunk behind the dorsal and pelvic fins, followed by the sides of the abdomen, and a few occur in the front of the fish body. A circular red spot first appears in the affected part, like a red seal stamped on the fish's epidermis, followed by epidermal rot, the scales in the middle part fall off, the rotten epidermis also collapses and falls off, and the white dermis is exposed. The scales around the lesion are buried in the rotten epidermis, and the peripheral scales are loose and congested and inflamed, forming a distinct outline. In the middle and late stages of the disease, a pot-bottom shape is formed. In severe cases, the muscles even rot, exposing the bones and internal organs, and the sick fish dies immediately.

[Prevention and treatment methods]

(1) Be careful when grafting and transporting fish and do not injure the fish. The fish pond should be thoroughly cleaned with quicklime, and the stocking density should be adjusted appropriately when stocking. Fresh water should be added frequently to keep the water in the pond fresh, which can prevent or alleviate the disease.

(2) Use 1 gram of bleaching powder per cubic meter of water and sprinkle it all over the pond.

(3) Use 10 grams of Chinese gallnut per cubic meter of water and sprinkle it all over the pond.

(4) For every 67 square meters of water surface, add 0.75 kg of chili powder and 10 to 15 kg of water, boil it, and sprinkle it evenly throughout the pond for three consecutive days.

(5) When the broodstock are sick, you can choose to inject chloramphenicol or chloramphenicol at 5 mg per kilogram of fish, or inject tetracycline at 2 mg per kilogram of fish, by intramuscular or intraperitoneal injection, and at the same time, apply bactericidal drugs such as potassium permanganate to the lesions.

Symptoms like perforation are bacterial infections. You can't see what kind of bacteria it is with the naked eye. It has worsened... and may cause blood poisoning. If you don't want this to happen, you should try to avoid injuring the fish. If you accidentally touch it, you should find it early and disinfect the wound, and keep the water clean...

Pox

[Pathogen] Herpes virus.

[Symptoms] In the early stage of the disease, many white spots appear on the body surface of the diseased fish, covered with a layer of white blocky mucus. As the disease progresses, the number of white spots continues to increase, and the area of ​​the spots continues to expand, causing the epidermis of the lesion site to gradually thicken, forming a paraffin-like growth that looks like a pox, so it is called "pox disease." When the pox grows to a certain size, it will fall off naturally, and then a new pox will appear again in the original affected area, eventually causing the fish to lose weight and die.

[Epidemic situation] It mainly harms carp, crucian carp and round-bellied croaker, affecting the growth of fish and reducing their commercial value. It can cause the death of sick fish in the late winter. The disease is prevalent in winter and early spring when the temperature is low (10-16℃), and in ponds, reservoirs and cages with fertile water. It will gradually heal itself when the water temperature rises.

[Diagnosis] A preliminary diagnosis is made based on symptoms and prevalence. Confirmation requires ultrathin sections of the growths, observation of the herpes virus under a transmission electron microscope, or isolation and culture of the herpes virus.

[Prevention and treatment methods]

1. Strengthen comprehensive prevention measures and strictly implement the quarantine system;

2. In endemic areas, fish species that are not susceptible to the disease should be raised instead;

3. Raising the water temperature and properly diluting the water also have a preventive effect;

4. Chloramphenicol was used for treatment. Each sick fish was injected with 25 mg intramuscularly and bathed in 0.225x10-6 chloramphenicol aqueous solution, which had a certain therapeutic effect.

Sprinkling chloramphenicol powder directly on the fish should also be effective. Soak the fish in chloramphenicol solution or chloramphenicol powder plus sulfamethoxazole solution, or gentamicin solution. How long should the fish soak?

Generally, low concentration takes about half an hour. High concentration takes about ten minutes. You can control it flexibly...

Bacterial infection: usually caused by poor pond water quality, frequent pecking of algae on the pond wall, or excessive fishing and transportation operations that cause fish injuries...

Symptoms: The body color of the diseased fish turns black, it swims alone, moves slowly, the epidermis of the lip tip becomes inflamed and eroded, and in severe cases, the fins are rotten and there are many slime molds on the body surface.

Prevention and control methods: Use quicklime to thoroughly clean and disinfect the pond, keep the water fresh, and frequently use quicklime to disinfect and adjust the water quality. Sprinkle 1mg/L bleaching powder throughout the pond. Bath the sick fish in 3% salt water for 10 minutes, and feed them with oxytetracycline powder, 2g per 10kg of fish per day, and a course of treatment of 3 days.