三、寄生虫病 1、口丝虫病病原体为口丝虫Ichthyobdo necator,属鞭毛虫纲,游动时呈豆形或椭园形,两根鞭毛,固着时近梨形。长5～20μm(平均约10μm),宽2.5～10μm(平均约4μm),鞭毛长9～18μm。是一种专性外寄生虫,寄生鱼体表面。分裂方式繁殖。离开鱼体成球形,0.5—1小时死亡。接触鱼体便寄生其上,尤其高密度养殖,这一寄生过程完成的很快。口丝虫经常引起大量死亡,尤其是网箱 Third, the parasitic disease 1, oral filariasis pathogens Icelia filariasis Ichthyobdo necator, is flagellate insects, swimming was a bean-shaped or elliptical, two flagella, fixed near the pear-shaped. 5 to 20 μm in length (about 10 μm on average), 2.5 to 10 μm in width (about 4 μm in average), and 9-18 μm in length. Is a specialized ectoparasite, parasitic fish body surface. Split way to breed. Leave the fish into a ball, 0.5-1 hours of death. Parasitic contact with the fish on it, especially high-density farming, the parasitic process completed quickly. Mouth filariasis often causes a large number of deaths, especially cages