In the parasites of freshwater fish, if according to their degree of harm, in terms of lethality alone, small fry of 12-14 mm, when there are 20 to 40 such insect bodies parasitic on the body, the fry will die in 7 to 11 days. Such a parasite, deservedly can be called the ace killer of parasites, which is the ringworm.
There are many types of ringworms, and more than 400 kinds have been found in China, but the main causes of disease are small sheath ringworms, gill ringworms, squid ringworms and bad gills ringworms. Ringworms are obviously selective to fish species, such as carp ringworms that parasitize on flower carp, small sheath ringworms that parasitize white carp, page ringworms that parasitize grass carp, and bad gills ringworms that parasitize carp, crucian carp and goldfish. Several of these parasitize the small sheath ringworm on silver carp, with the largest body and reaching a length of up to 1.4 mm.
The harm of ringworms is mainly determined by the unique structure of its tail suckers, the center of the suction cup has a pair of large hooks piercing into the gill tissue, and seven pairs of small hooks on the edges into the epithelial cells, tearing the gill tissue, causing gill bleeding, causing the fish to breathe, and then causing secondary infection of fungi and bacteria, further causing dead fish. On naked eye examination, the gills are pale and swollen, with more mucus on the gills and gills, and the gill cap is difficult to close, and the ring worm can be initially listed as a key suspect.
The most common monocultural trematodes in carps, gill ringworms, gills and page ringworms are commonly found on grass carp, while most of the parasites on the white carp are small sheath ringworms and bighead carp, and most of the parasitisms on carp, crucian carp and goldfish are bad gill ringworms, there are many genera and species, and show a certain degree of selectivity to the host.
Ringworms are transmitted through eggs and larvae. Ringworms are oviparous, with large and few eggs. The rate and rate of development of eggs by the insect body is greatly affected by temperature, when the water temperature is lower than 3 degrees, the eggs do not develop, when the water temperature is 20 degrees, it can hatch in 4-5 days, at 22-26, it can be hatched in 3 days, at 18-19 ° C it takes 5-6 days, and when the water temperature is 16-17 ° C, it takes 8-9 days. The rate of egg development increases as the water temperature decreases, with 70%-80% of eggs developing at 16-17°C and only 20%-30% of eggs developing at 22-26°C. Therefore, the incidence of ringworms is mainly in late spring, summer and early autumn.
Ringworms mainly harm summer flower and spring flake fish species, such as 12-14 mm and 18-20 mm stages, like 12-14 mm small fish into the source of infection, the fish body with 20-40 worm bodies, the joint death takes 7-11 days. According to statistics, the larger individuals have 400 ringworms per fish, which causes death. Ringworm disease is identified when 50 worm bodies are found on a gill patch or 5-10 worm bodies per field of view under low magnification microscopy. At the same time, in the recent treatment of grass carp gill disease, if a ring worm is found, it will delay the number of days of cure.
Ringworms have four eye spots that are absent from three generations of worms
Ringworms are hermaphrodites, there are eggs in the tail, sperm under the egg, mature ringworms in the water temperature of 20 degrees, an hour can lay more than 10 eggs, once encountered external stimuli, ringworms have the desire to instinctively continue the species, will accelerate spawning, and some are used to laying more in the evening. The eggs laid by the ringworm are sinking eggs, which will sink to the bottom of the water, and at a water temperature of 20 degrees, ciliated larvae will hatch in 4-5 days, parasitize when they encounter a suitable host, and can reproduce as long as they pass more than 20 days. When killing ringworms, it is possible to:
First, if the bottom water can be drained after insecticidal, then the extraction of the bottom water will help improve the insecticidal effect, especially the river cage, moved to the middle of the river to apply the drug, and dragged back to the original place after application;
The second is to use the worm egg is a ciliate, and use it to have phototropism to kill insects;
The third is to use the incubation cycle of insect eggs, which is particularly serious and can be applied again after 5 days.
For the use of ringworms, mebendazole is often used, but scaleless fish are used with caution, especially like forktail catfish and yellow mulberry fish (can be used without scale ring net). Occasionally, some people feedback that the killing effect is not good, and it is recommended that you can switch to an internal insecticide, such as intestinal insect net.
Most of the drugs commonly used to kill ringworms are mizoles, high cost, strong resistance, such as ring qing, water agent 250 ml can be used for 3 acres, scaleless fish is prohibited to use mizole drugs, such as spotted forktail catfish, largemouth catfish, etc., in these fish to kill ringworms to choose special insecticides, such as scaleless ring net, 100 ml a bottle with 3 acres. It can continue to effectively deworm, up to more than 5 days, kill adults in the early stage, inhibit egg laying in the later stage, just equal to the hatching cycle of ring worms, so the effect is good at the same time.
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