Study On The Trichodinid Ectoparasites (Ciliophora: Peritrichida) From The Gills Of Freshwater Fish, Carassius Auratus, In Chongqing

This work mainly deals with ectoparasitic trichodinids from freshwater fish, Carassius auratus in Chongqing. All the work falls into 3 sections. In the first section, 23 trichodinids including 8 new species and 10 first recods were described, and these new species contain the trichodinids as below: Trichodina paranigra Tang, Zhao & Chen, 2005, Trichodina pachyhamata Tang, Zhao & Tang, 2005, Trichodina brevicirra sp. nov., Trichodina crenula sp. nov., Trichodina subtilihamata sp. nov., Trichodina foraminihamata sp. nov., Trichodina albi sp. nov. and Trichodinella nova sp. nov. The morphological and taxonomic research on trichodind was based on observation of living body, dry silver impregnation technique, methyl green-pyronin stain (Foissner, 1991) and so on.In section 2, we also carried out the histopathological study on the gills of Carassius auratus infested seriously by a trichodinid, identified as Trichodina heterodentata Duncan, 1977. The result of our study indicates that while a heavy infestation with this ectoparasites can interfere with respiratory function of the gill (Lorn & Dykova, 1992) as a result of excessive mucus production which covers the lamellae. The physical irritation and change of the superficial epithelium parasitized by the ciliates, together with the inflammatory response of the host, inevitably cause respiratory impairment. So a heavy parasitic infestation of the gills may prevent gas exchange and death of the host may occur as a result.Based on the ecological survey of the trichodinid from LongShui Lake in Dazu County, the result of survey shows: Trichodinella epizootica (Rabbe, 1950) Sramek-Husek, 1953 was the dominant population of trichodinids in LongShui Lake. From November to December, prevalence of Trichodinella epizootica reaches its minimum, whereas from July to August, prevalence reaches its maximum. According to the correlation between prevalence and water temperature, the both are positive correlation when water temperature is between 10C° and 34C°.