How to prevent gill rot in fish!

Fish diseases, as is the common gill disease, in the "old three diseases", sepsis and outbreaks, complications, comprehensive diseases and other fish diseases have "rotten gills" to varying degrees of accompaniment, grass carp in fish are most susceptible to rotten gill disease, where fish with gill disease are "rotten gills" as the main symptom of performance, although it is a common disease but is not easy to cure one of the fish disease, although it is a common disease but it is the most likely to cause death of the main fish disease.

First, the gills are the respiratory organs of the fish, just like the human trachea and lungs, is the only channel for absorbing oxygen, can not absorb oxygen or insufficient oxygen intake will cause body disorders, and the human body analogy, fish gill disease can also be called fish (bronchitis) or fish pneumonia.

Second, the entire body of the fish has a protective layer (fish scales and body surface fluid, the mouth is also considered to have pharyngeal protection), but the gills in the gills of the fish are full of fine blood vessels and tender and brittle, without protection of protective substances, directly in contact with water and all objects (substances) in the water body, so they are most vulnerable to intrusion.

Gill rot disease is a "common disease" caused by the lack of protective layer of the gills of fish and contact with water and all objects (substances) in the water body.

Gill rot disease "most likely to cause death" is because the gills of fish are the only channel for absorbing oxygen, and they are the most important material basis for the survival of fish.

Gill rot disease of fish is mainly divided into four categories: parasitic gill disease, bacterial gill disease, gill disease caused by deterioration of water quality, and fungal gill disease.

At present, it is mainly based on parasite-induced gill rot and bacterial gill disease, and there are few reports of viral gill disease and other diseases.

Due to the special "direct contact with water and all objects (matter) in the water body", water quality improvement is the top priority, increasing dissolved oxygen is also a top priority, parasites and bacteria mostly breed at the same time, insects and bacteria double kill.

The asexual reproduction of wheelworms takes a 24-hour cycle and is divided into four stages (pre-column, divisional, developmental, and mature). Larvae, child worms and adult worms can infect the host and affect its growth and development.

(2) Blocking effect. Through the synergistic effect of the tooth ring and the marginal membrane, the wheelworm can produce a strong adsorption force, tightly adsorb on the surface of the host tissue and can produce a certain degree of damage to the gill epithelial cells, mucus cell proliferation, capillary congestion and exudation on the gills.

In addition, when the insect body occurs in large quantities on the surface of the host gills, it can stimulate the gill tissue to secrete a large amount of mucus, so as to block the smooth flow of water, interfere with the exchange of gas between the gill filament and the outside world, resulting in a decrease in appetite due to lack of oxygen, slow metabolism, and even death in severe cases.

Mainly the gill tissue rot, gill filament cartilage exposed, gill cover edge and gill filament gap by a large number of wheel worm parasites, gill blood loss, severe gill filament local ulceration, grayish yellow, serious impact on the fish's respiratory function, causing breathing difficulties, stop eating, so that the fish lack of oxygen, and eventually suffocate to death.

The peak season of the epidemic is May-August, which is most likely to occur in ponds where fry grow into summer flower fingerlings. In the case of continuous rain, it is easy to cause the epidemic of this disease.

Ringworm hermaphrodites, oviparous, few, large, oval-shaped. Fertilized eggs hatch one larvae, one parasitize one adult, one fertilized egg, with an average lifespan of 1 month.

Adults continue to lay and hatch during the warm season, and after the self-fertilized eggs are released from the worm body, the eggs float on the surface of the water or attach to other objects or host gills and skin. The larvae emerge from the eggs and fall into the water to become free-swimming ciliated larvae.

Ciliate larvae have phototropism, use the head organ to identify the host, when can not find a suitable host, will also die, encounter a suitable host on the attachment parasite, after the body attaches, remove cilia, the organs are formed, growth and development into adult worms, the next round of life history begins.

Ringworms mostly parasitize secondary gill filaments of fish, the posterior sucker inserts into the secondary gill filaments of fish, the central hook protrudes into respiratory epithelial cells or pierces into capillaries, and the small edge hook hooks the gill filament tissue, protrudes into the respiratory epithelial cytoplasm and tears the cells, resulting in gill filament epithelial ulceration and microhemorrhage, gill fusion, hyperplasia and necrosis.

In moderate infection, the diseased eel has decreased appetite, increased gill mucus secretion, gill flap congestion, abnormal gill cap undulations, slow swimming weakness and weakness;

In severe infection, the sick fish does not feed, breathes quickly or breathes in a single gill, the gills are severely hyperemic, the gills are defective, and the pectoral fins are congested and red;

When examining the gills of the diseased fish, it is found that it is covered with red mucus, gill smudges, hyperemia, hyperplasia, breathing ability is greatly weakened and causes breathing difficulties, and the diseased fish swims alone or wildly on the water surface, causing death or mass death.

Some sick fish body color is black, the whole body mucus increases, especially the gill cover has more mucus, the gill filament is obviously puffy (the gill cap is not solid), open the gill cover, the gill filament appears black red or light red, the gill tissue is covered with mucus, the gill lid is open, the gill filament loses blood or the gills, the fish body is slow to react, stop eating when severe, and eventually suffocate due to breathing obstruction.

Microscopic examination under 10 * 4 times the microscope, you can observe the worm body peristalsis, the naked eye can sometimes see that there are many ring worms under the mucus to form a 'small white dot'.

Both asexual reproduction and sexual reproduction are carried out and completed in a single parasite, with no intermediate host.

After the spores that fall into the water in the diseased fish with sticky (slimy) sporidium are eaten by other fish or contacted by other fish and adhere to the surface of the fish body or on the gills, they are stimulated by certain substances in the body to release the polar filaments, the shell is cracked, and the spores inside become amoeba-like bodies, invade the tissue cells and settle down, and begin to grow and develop.

After repeated divisions of the spore nucleus, a large number of spores are formed, and the sporosomes are stimulated to change to form sporangia, which are generally visible to the naked eye.

Myxosporidium, which parasitizes on the surface and gills, is finally squeezed by mature spores, which are scattered directly into the water, re-invading other fish bodies, and beginning to repeat its life history.

Silver carp, bighead carp, carp, crucian carp, grass, etc. can be infected from fry to adult fish. After parasitizing the gills of the fish body, the cysts gradually increase, destroying the gill tissue, and the gill cap is incompletely closed, resulting in difficulty breathing, hindered growth and development, and eventually causes a large number of deaths.

Generally, there are many white dot-like or lumpy sacs in the epidermal tissue of the gills, which are easily visible to the naked eye, puncture the cysts, and a large number of myxosporidia can be seen on microscopic examination.

Generally early summer onset, carp is most likely to develop this disease, with the increase of temperature, sporangia sac grow larger and larger and gradually rupture, the damage to the gills is also more and more serious, after entering the high temperature season in July, it is more likely to cause bacterial infection.

The second pair of antennae of the Chinese gill becomes a large slender hook that attaches to the gill filament of the fish. After the female worm matures, the reproductive node has a pair of slender white oocysts, after a few days or more than ten days of eggs hatching a nodular larvae, can live freely in the water, after 4 times of peeling to become the fifth section of larvae, and then peeled once to become the first copepod larvae, 4 times to become the fifth copepod larvae, and then after 1 peel to become a juvenile loach.

The worms mate in the fifth copepod larvae, and the mating males can still live freely in the water until death, while the female gills use large hooks to hook on the gills of the fish, invade the host to live a parasitic life, and the body grows several times to maturity, repeating its life history.

Chinese gill parasitizes on the gills of fish, in addition to the large hook hook to break the gill tissue, seize the fish nutrition, it can also secrete a substance of enzymes, stimulate the gill tissue, make the tissue hyperplasia, so that the gill filament end of the diseased fish swollen white, deformed, serious, the entire gill filament at the end of the gill flap edge is swollen and white, even rotten, affecting the fish's breathing. The wound at the parasite causes bacteria to invade, causing local inflammation of the gill filaments and causing the fish to die.

The gill filament end of the diseased fish is swollen and white, deformed, and in severe cases, the gill flap edge of the entire gill filament is enlarged and white, the mucus on the gill increases, the sick fish has difficulty breathing, is restless, and is swirling or swimming wildly on the surface, and the upper lobe of the tail fin is often exposed to the water. The gills are hung with maggot-like insect bodies, so it is also called "gill maggot disease".

In addition to the above several types of gill rot caused by parasites, there are parasitic diseases such as oblique tube worms, gill cryptoflagellus, etc., which are similar and not one by one.

1, with copper sulfate and ferrous sulfate compound (5:2) sprinkled in the whole pool, so that the pool water into 0.7-1ppm concentration;

3, with 20 g / m3 potassium permanganate solution medicinal bath for 20 min, can kill fish fingerlings parasitic larvae.

4, the whole pool is sprinkled with 90% crystalline insects, so that the pool water reaches a concentration of 1-2 grams/m3 (the minimum amount of insects is 1 gram per cubic meter of water body, the highest can not exceed 4 grams).

6, the commercially available insecticide containing parasites is used for two consecutive days, and the third day is used with a bactericidal drug, which can generally be cured.

Gram-negative bacteria, Columnar xanthobacterium, Mycoccus fish pest, Aeromonas hydrophila and Mild Aeromonas.

The bacteria are conditionally pathogenic bacteria, in general, healthy fish are not susceptible to infection, environmental pressure or tissue damage can easily lead to the occurrence of the disease. Columnarella secretes an enzyme that degrades acidic polysaccharides, which degrades hyaluronic acid and chondroitin sulfate. Chondroitin sulfate causes tissue damage by degrading chondroitin in the extracellular matrix of fish tissue.

At the beginning of the disease, the gill mucus increases, and in severe cases, the skin on the inner surface of the gill cover of the sick fish is hyperemia and inflammation, the skin inside the gill cap is congested, the middle part is often eroded into a round or irregular transparent window, the gill filament end necrosis, cartilage is exposed, and the gill tissue rots, commonly known as "open skylight".

There is a lot of mucus on the gills, the gill filament is swollen, some parts of the gills are reddish or grayish-white due to local ischemia; some parts are purple-red due to local congestion, and even small bleeding spots; in severe cases, the gill fragments are necrotic and fall off, the gill filament is defective, the gill filament is exposed; around the diseased gill filament, necrotic cells, mucus, columnar flexia and various debris in the water are often adhered.

1, according to each cubic meter of water with bleach powder 1-1.5 grams of the whole pool sprinkled, for 2 days, or with other disinfectant drugs sprinkled in the whole pool;

3, timely use after the onset of the disease: bromochlorohydantoin 0.3 g / m3, the whole pool is sprinkled, and the whole pool is sprinkled once every two days when the disease is severe;

4, andrographis internal: per 100 kg of fish reuse dry andrographis 0.5 kg, boiled for 2 hours mixed with feed feeding for 3-5 days.

5, with 0.3 g - 0.6 g / m3 of sodium dichloroisocyanurate (euchlorin) or 0.2 g - 0.5 g / cubic meter of trichloroisocyanuric acid (strong chlorine) spilled in the whole pool, for 3 days - 4 days, or with hanging bags treatment;

6, povidone iodine for internal fish, per 100 kg of fish per day dosage of 25 grams, mixed feed feeding, continuous use for 5 days for a course of treatment;

7, the whole pool is sprinkled with rhubarb liquid or five-fold sub-liquid, and the dosage is 2.5 grams - 4 grams / cubic meter;

8, when the pool water is acidic or partially acidic, the whole pool is sprinkled with quicklime slurry water 10-15 kg/mu;

10, cigarettes or tobacco leaves: cigarettes 180-200 g / m3 or tobacco leaves 3-4 kg / m3 or boiled water soaked for half a day after the whole pool is spilled.

Gill mold. The pathogens of gill mold are The order Dentalis, Blastocladiaceae, and branchiomycessp.

Grass carp parasitic gill mold, its mycelium is relatively straight and less curved, usually unipolar prolonged growth, few branches, does not enter blood vessels and cartilage, only grows in gill small pieces of tissue. The mycelium is 20-25 microns in diameter and the diameter of the spores is 8 microns.

The other parasitizes in the gills of bluefish, bighead carp, and gill, its hyphae are often curved into a net, thin and thick walls, with many branches, branches grow along the gill filament blood vessels or afferent cartilage, from the transverse staggered gill filament and gill pieces, the mycelium diameter is 6.6-1.56 microns, and the spore diameter averages 6.6 microns.

Gill mold is generally considered a conditional pathogen, and when the surface of the fish is injured, or infected with other pathogens, or improperly managed in feeding, and the fish's own immunity is low, the gill mold's zoospores, oospores, and fragments of mycelium sticking to the mucus on the surface of the fish body multiply on the surface of the fish body, resulting in infection of the fish or fish eggs.

There is no obvious abnormality in the surface of the fish body when observed with naked eye of gill mold disease, but the gill filament is swollen, the mucus is increased, and the local congestion is dark red or anemia is whitish.

Sick fish have difficulty breathing, no appetite, increased mucus on the gills, bleeding, bruising and ischemic plaque, commonly known as "spotted gills". In severe cases, the entire gills are bluish grey.

Acute type of disease fish infected with gill mold caused by gill mold parasitism on the gills of the gills, manifested by gill bleeding, part of the gill filament is pale in color, the fish do not feed, a large number of deaths within a few days after the appearance of the disease, chronic type of diseased fish, necrotic gill filament part rots and falls off, gill anemia, pale color, mortality rate is slightly lower.

Gill mold disease mainly occurs in ponds with deteriorating water quality, high organic matter content, and turbid water quality with more organic matter, and smelly fish ponds are most prone to this disease.

3, use products with killing effect on fungi at least once a month during the high temperature period. For example, benzalkonium bromide + glutaraldehyde and the like.

The forms of nitrogen in the pond are: nitrogen, molecular ammonia, ionic ammonium, nitrite, nitrate, organic nitrogen (amino acids, proteins, humus), where molecular ammonia + ionic ammonium = total ammonia nitrogen (TAN).

When the molecular ammonia exceeds the standard (the maximum ammonia concentration that fish can tolerate for a long time is 0.025 mg / liter), it interferes with the gill osmotic pressure regulation system, damages the structure and function of the gill filament mucosa, the fish is affected by the effect of ammonia, and when the concentration of molecular ammonia in the blood is high, the PH value in the fish blood is correspondingly increased, thus affecting the activity of a variety of enzymes in the fish, ammonia poisoning occurs, and eventually leads to the death of the fish.

When the nitrite exceeds the standard, nitrite due to the combination of oxygen-carrying protein in the blood of the fish body, resulting in a decrease in the efficiency of oxygen carrier in the fish body, physiological hypoxia, when the concentration of nitrite in the water accumulates to 0.1 mg / l, the number of red blood cells and hemoglobin in the fish and shrimp is gradually reduced, and the blood oxygen carrying capacity is gradually reduced, resulting in chronic poisoning of fish and shrimp, at this time, the amount of fish and shrimp feeding is reduced, the gill tissue lesions occur, breathing difficulties, agitation or slow response, and in severe cases, fulminant death occurs.

2, increase dissolved oxygen is a top priority, as soon as possible to take measures (the application of water modifiers, algae seeds, bottom modifiers, etc.) to improve water quality.

3, poor water quality caused by gill disease will also occur but not limited to the above several types (parasitic gill disease, bacterial gill disease, fungal gill disease, etc.), to visual inspection, instrumentation, microscopic examination to confirm the disease, due to different symptoms and the use of the above different treatment methods.