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There are "blood" spots, blood spots, and erythema on the body or scales of the fish, and in general, the large parasite --- the fish is the anchor-headed loach (fleas), also known as stinging worm disease, needle worm disease, or epilepsy disease, because when the anchor-headed loach is seriously erupted, the body of the insect body is covered with fish as if it were draped in a coat. Loach, according to the current pronunciation is riot "burn", flea, pronounced as the "early" of water fleas, therefore, according to the pronunciation, it should be "anchor head flea" name may be correct.
1. Pathogens
The pathogen of fish anchor-headed flea disease is caused by the parasitism of the fish parasite anchor-headed flea in fish bodies. The anchor-headed flea is a species of crustacean arthropod that is a directly developing species with no intermediate host. Only female adults live permanently parasitically, and both larvae and male adults live freely. The head of the anchor-headed flea body, that is, the "anchor head", drills into the muscles of the fish body, and then uses the mouthpart to suck the blood of the aquatic animal to survive.
Male anchor-headed fleas always maintain the body shape of sword water fleas, while female anchor-headed fleas vary greatly, with elongated body shapes, tubular and twisted joints, and head horns growing on the cephalothorax. The adult anchor head flea is about 1 cm long, the rear end of the worm body has a pair of egg sacs, and the front end of the worm body has forked horns, similar to the anchor, and because the worm bites in the fish body, it is shaped like the anchor head used when the hull is docked to fix the anchor head, and also bites on the fish body like an "anchor head grip", so it is called the anchor head flea (loach).
(Sword flea: Anchor-headed flea males always maintain the body shape of sword fleas)
("Anchor" into the water when the hull is docked)
(Anchor head flea body)
("Anchor" when the hull docks on the waterfront)
There are four common types of anchor-headed fleas: the most harmful to fish is the polymorphic anchor-headed flea.
1. Parasitize silver carp, bighead carp body surface and oral cavity called polymorphic anchor head flea. When parasitized in the oral cavity, it can cause the mouth to not open and close, so it cannot be ingested.
2. Parasitic grass carp scales are called grass carp anchor head fleas.
3. Parasitizing the gill bow of the grass carp is called the four-ball anchor head flea.
4. Parasitizes carp, silver carp, bighead carp, mullet, goldfish and other body surfaces called carp anchor head flea.
(Erythema and insectoids that appear on grass carp)
2. Symptoms
Anchor-headed fleas are one of the most common, stubborn and difficult ectoparasites in fish farming. When the anchor-headed flea parasitizes the fish body, the head of the female adult worm burrows into the muscle tissue, and the rear half is exposed and visible to the naked eye, as if a small needle is inserted into the fish body, so some people call it "needle worm disease".
The parasitic site of anchor head flea is red, swollen, inflamed and suppurative, and the swelling of the parasitic site is more obvious. Anchor-headed fleas mainly attack the surface, gills and mouth of fish, absorbing nutrients from the fish. The tissues around the site where the anchor head flea drilled in are inflamed, red and swollen, and erythema appears due to bleeding. This causes the fish scales to crack. Sick fish are irritable, thin, and the fish often rub parasitic parts on aquatic weeds and stones when they are painful and itchy, and scurry in the water, causing "noisy ponds", loss of appetite, and slow movement.
When the anchor-headed flea parasitizes on the surface of the fish body with small scales such as silver carp and bighead carp, it causes redness and swelling and inflammation around the parasitic part, forming a red spot that is obviously pomegranate-like, and the swelling of the parasitic part is more obvious; when it parasitizes the surface of the fish body with large scales such as carp and crucian carp, the scales of the parasitic part are often "moth" into a gap, and the swelling of the parasitic part is not obvious, but the formation of hyperemic erythema.
The "red spots" and "erythema" we see are due to the fact that the head of the female adult of the anchor-headed flea burrows into the tissue tissue of the fish body, causing tissue-cutting bleeding and inflammatory response, with a large number of lymphocytes, eosinophils, monocytes, neutrophil infiltration and fluid exudation; edema occurs in the tissues around the parasitic site of the worm, and the tissues near the insect body are necrotic.
(Anchor-headed flea body removed from fish)
3. Epidemic status
Anchorhead fleas can invade species such as carp, crucian carp, silver carp, bighead carp, grass, mandarin, California perch, etc., and most fish can be infected with parasitism. The harm to juvenile fish is particularly serious, can cause death, has less impact on large fish, and most mainly affects the growth rate and the value of the commodity that affects the appearance, and generally does not cause dead fish. The epidemic area of this disease is wide, and it has been found in all fish farming areas in the country, which can be seen all year round, and summer and autumn are the period of serious epidemic outbreaks.
Anchor flea can breed at a water temperature of 12-33 ° C, the breeding temperature is 20-25 ° C, when the water temperature exceeds 33 ° C, not only can not reproduce and adult insects will also die in large numbers. Its life span is closely related to the level of water temperature, the longest life is 5 months to 7 months, and the shortest life is only about 15 days. When the water temperature is low, the eggs will sink into the bottom mud, and sometimes the larvae will dive under the fish scales for the winter, and when the water temperature reaches about 15 ° C, it begins to breed.
According to some people in practice, lean water is prone to anchor head falter parasitism, and fat water is rare or difficult to have outbreaks of anchor head flea parasitism.
Fourth, similarities and differences
The anchor-headed flea inserts the "anchor head" of the head under the scales of the fish, and uses a "anchor-head" mouth suction device to bite into the fish to suck blood to feed itself, and the scales in the parasite often fall off, and erythema of blood spillage appears. This is the most obvious feature of anchor-headed fleas after parasitism. Blood spots or blood spots appear on the scales of the fish body, which are similar or similar to the "bleeding disease" or congestion symptoms that we have long known, and may sometimes be mistaken for a bleeding disease. Symptoms of bleeding disorders or congestion are contiguous, and the erythema of anchor-headed fleas is mostly dotted or patchy.
(Crucian anchor-headed flea disease: erythema or spots on the body surface)
(Crucian carp body surface bleeding or congestion symptoms)
Anchor-headed flea bodies can parasitize various parts of the fish body and initially appear as white-lined heads (larval stages) that swim with the fish. Some insects have cotton wool moss on their bodies, which are often mistaken for moss and hang on fish. The surrounding tissues of the anchor-headed flea parasite are often red, swollen and inflamed, while the scales near the wound are dissolved by the secretions of the anchor-headed flea and corroded into a notch. If the erythema is only seen and the insect body is not seen, it may be that the anchor-headed flea is still in the larval stage.
(Fishtail parasitic anchor-headed flea body)
Fifth, development characteristics
Anchor-headed flea first discharge of the worm eggs hatched into a nodular larvae, after 5 times of molting into copepod larvae, copepod larvae and then molted 4 times, it takes 3-4 days, when the anchor-headed flea in the fifth copepod larvae, reach sexual maturity, after mating on the fish body, the female anchor-headed flea to find a suitable host, began to parasitic life.
Observe the morphological distinction between the adult anchor flea: when killing the anchor flea, it is actually killing the larvae in the water, and it is difficult to kill the adult insects. Therefore, observe and judge the morphology of adult insects to judge the larvae in the water body, and take targeted killing according to the life history of the insect body.
The child is like a fine hair, without oocysts, and there are blood spots on the parts of the parasitism on the fish body.
The body of the worm is transparent, the ink-colored intestinal peristalsis in the body can be seen, the ovaries occupy a prominent position on both sides of the intestine, and the posterior end of the body often has 1 egg sac, which can be erected when the body is moved by hand.
The old insect's body is cloudy and soft, and there are many tired branches on the surface of the body.
The life history of anchor-headed fleas is divided into three stages: arthropods (larval stage), copepod larvae (adult stage) and old worm stage. Anchor-headed fleas mate at the 5th copepod larvae, only once in a lifetime. When the ambient water temperature is 18-20 °C, it takes a total of 5-6 days from hatching to the first copepod larvae; when the water temperature is around 25 °C, it takes 3 days; when the average water temperature is up to 30 °C, it takes only 3 days.
(Crucian carp body surface erythema --- anchor-headed flea larvae, possessed larvae)
Sixth, the difficulty of insecticidal
Usually, the reason why it is difficult for us to kill the anchor head flea is that after growing into an adult worm or a strong insect, the anchor head head is deep into the muscle under the scales of the fish, and most of the drugs are difficult to pass through the fish body and then enter the anchor head flea body, which is the root cause of the anchor head flea being difficult to kill.
Once the outbreak of anchor flea is difficult to control, it is easy to recur repeatedly. Some people have proposed that the fish body can be immunized after the infection of anchor flea is cured, but in fact, after years of practice, it has been found that the fish body will still parasitize or completely occur in the second year after the onset of the disease, and the "immunity" talk is impossible to talk about.
In the stage of the worm, the "anchor" head is deeply inserted into the fish body, and only the trunk node of the worm body is exposed. According to some experiments, even if it is soaked with a high concentration of insecticides at this time, when the soaking is unbearable for the fish, it may not be able to kill the anchor-headed fleas parasitic on the fish body.
(Anchor-headed flea in the robust stage)
7. The number of insecticidal drugs
The weak link in the life history of the anchor-headed flea can only be effective with drugs, and its weak link is undoubtedly the autistic larvae or copepod larvae that are not yet possessed by the fish and are still in the free life stage. Because once the anchorhead loach parasitizes the fish body, whether it is in the "larvae", "adult" or "old worm" stage of the worm body, because the worm body has deeply invaded the muscles of the fish body, it is no longer disturbed by the outside world. Therefore, it is actually difficult to exert an effect on the various drugs that are spilled on them. That is to say, the purpose of sprinkling various insecticidal drugs is not to kill the adult insects on the fish body, but only to kill the anchor-headed flea larvae that are in the stage of free life and control their continued reproduction.
In order to completely eliminate the anchor fleas in the water, it is necessary to drug 2 to 3 times in a row. There is a question of how long the interval is. Some people have a method to calculate by multiplying the water temperature by the number of days equal to 100, that is, the water temperature is only 5 days apart at 20 degrees, and when the water temperature is 15 degrees, the interval is 7 days, and so on. But the total interval is roughly five to seven days (around a week).
If the fish body is mainly infected with small white anchor-headed flea "larvae" without egg sacs, it can be used twice in half a month; if it is mainly an anchor-headed flea "adult" with a transparent body with green oocysts, it can be used once; if the insect body is cloudy, the anchor-headed flea "old worm" is more, because the old worm stage is the end of life, it can be ignored or temporarily not used.
If there are not many parasitic insect bodies in the general fish, or immediately enter the winter (below 12 ° C), or the weather season of high temperature (above 33 ° C), the anchor head flea body will mostly kill itself or the egg body will hibernate in the mud, which can be temporarily ignored.
8. Suggestions for insecticidal methods
For ornamental fish raised by large individual precious fish or small water bodies (including aquariums), the diseased fish can be fished out when suffering from the disease, and the anchor head fleas can be directly removed with forceps and applied with anti-inflammatory drugs. It is said that the larvae of the anchor-headed flea have weak phototropism, and when they are not possessed by the fish, they like to concentrate on the water surface in the morning and evening, so the medication time is better in the morning and evening, but it is advisable to turn on the aerator, and use this method with caution.
In addition, when using insecticides, in order to increase the efficacy of the drug, ferrous sulfate can be sprinkled before taking the drug. Ferrous sulfate has the effect of co-solubility and permeability, and the use of aquatic products is more to use it to eliminate the solids on the surface of the skin of the fish body, so that the mucosal cells fall off, increase the contact between the drug and the lesion and the parasite, and increase the permeability of the drug.
1. Insecticides
(1) Enemy insects and their compounds.
A. Crystal enemy insects. 0.5-1.0 g/m3 water body spilled, can be used again after 5-7 days. Note: Shrimp and crab polyculture ponds and fish ponds such as rainbow trout, white pomfret, mandarin fish, and California perch that are sensitive to enemy insects cannot be treated with enemy porphyra.
B. Diothoxylum copper sulfate mixture: per cubic meter of water, 0.5-1.0 grams of crystal diphtheria and copper sulfate 0.5-0.7 grams of mixture, the whole pool evenly or continuously sprinkled 2 times (days), 5 days after 5 days to use again. It can kill anchor-headed fleas and sporozoites.
C. Diphthora ferrous sulfate mixture: Crystal dimethoate and ferrous sulfate in a ratio of 4:1, the dose is 0.2-0.3 g / cubic meter; 2.5% powder and ferrous sulfate mixture 1.2: 0.2 whole pool sprinkling, so that the water concentration of 1.4 g / cubic meter, can control silver carp Chinese flea, fish flounder and so on.
(2) Cypermethrin, cypermethrin. Sensitive to aquatic animals, use with caution. Both are mainly used for the control and treatment of parasitic diseases such as anchorhead fleas, Chinese fleas, fish mackerels, three-generation insects, ringworms, and branches of fish. Dosage as directed or as previously safe.
(3) Avermectin, ivermectin. Widely used in killing all kinds of fish, shrimp, crabs, shellfish and other parasitic anchor fleas, Chinese fleas, fish flounder, nematodes, ringworms, three generations of insects and other parasites and branches, copepods, pine algae, water centipedes and so on. Water depth of 15 to 20 ml per acre per meter, or as directed or in previously safe doses.
(4) Octyl thiophos. It can be used to control parasitic diseases such as fish ringworms, three-generation insects, anchor-headed fleas, Chinese fleas, and fish mackerel. It also has a killing effect on branches and copepods. Shrimp and crab are prohibited. Dosage as directed or as previously safe.
(5) Potassium permanganate medicinal bath. According to the resistance of each variety to potassium permanganate, it should be treated separately. According to some experiments: for diseased grass carp, use 20 g/ m3 at water temperature of 15 ~ 20 ° C, use 10 g / m3 at water temperature of 21 ~ 30 ° C, and use medicinal bath for 1.5 to 2 hours; for diseased silver carp and bighead carp, use 33 g / cubic meter when the water temperature is below 10 ° C, 20 g / m3 at 10 ~ 20 ° C, 12.5 g / m3 at 20 ~ 30 ° C, 10 g / m3 above 30 ° C, and 1 hour in the medicinal bath, which can kill the larvae and adults of anchorhead bream, but the application is more troublesome in production.
(6) Apply special drugs for killing parasites (anchor head fleas) in the city. Theoretically, all fish insecticides (except copper sulfate) can kill anchor head flea parasites, such as enemy insects, mixed anthem, mixed Tean, fish worm net, mixed ann + fish worm net and other commercially available insecticides, and now there are also compound insecticides that are said to be specialized in killing anchor head fleas.
2. Earthwork insecticide
Because anchor head fleas are prone to drug resistance to fishing drugs, and commonly used fishing drugs are more toxic to fish, it is possible to overcome the above shortcomings by selecting some earthen methods to kill fish anchor head flea, but whether some methods are effective has to be verified.
(1) Use 30-40 pounds of neem branches and leaves, or pine branches and leaves, or maple poplar branches and leaves per acre, bundle and dip into the pool, or mash the leaves, soak in water for 24 hours, or after decoction boiling water, and sprinkle the whole pool with residue with juice. It is said that the anchor head flea falls off after three days, and according to practice, at least it is effective to prevent it in advance, including wheel worms, ring worms and so on.
(2) The average water depth of 1 meter per mu is sprinkled with 100-200 pounds of fresh lees, and it is said that the effect can be seen after 5 to 7 days.
(3) 10-20 catties of pig or cow blood per acre of water surface, sprinkled or mixed with the whole pool and fed, once every other day, 3 times. It is said to be effective against body surface parasites such as anchor flea, fish mackerel, wheelworm, third-generation worm, and ringworm.
(4) 1.6 kg of cottonseed and 0.4 kg of tung oil per mu of water surface, and the whole pond is sprinkled or mixed with ingredients and fed to the fish (the cotton roe is first fried and crushed, and then mixed with tung oil and fish feed).
(5) When the average water depth is 1 meter, 50 to 100 yellow jaw fish are stocked per acre of fishing ponds, and let them prey on the eggs of anchor loach or the larvae of the unfish body in the water body to avoid the consequences.
(6) Plankton in the water, such as branches and copepods, in their survival and growth, can feed on the eggs of anchor-headed fleas, small melon worms, and arthropods. It is said that there are more zooplankton, such as when the flea breeds vigorously, anchor fleas and small melon worms can be greatly reduced or even extinct.
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