Carassotrema schistorchis is a digenea parasite whose juvenile and adult stages parasitize the intestinal tract of definitive host fish. There is no available ecological information about this parasitic infection in wild host fish. The present work aimed to investigate the infection rate and distribution of C. schistorchis in wild silver carp, Hypophthalmichthys molitrix, and to assess the influence of environmental factors on infection by the parasite. From October 2016 to May 2019, a total of 554 wild silver carp were collected from two reservoirs. These collected fish were weighed, measured, and dissected to observe the presence of C. schistorchis following standard methodology. Ecological analysis results showed that the frequency distribution of C. schistorchis in the host population was aggregated distribution. The abundance of C. schistorchis exhibited a positive correlation with the host age and condition factor of silver carp, but it showed no relationship with water temperature, pH or DO. The condition factor value of infected fish was significantly higher than that of uninfected fish. These results indicated that food intake, not environmental factors, directly determined infection by the parasite in the host, indicating that an increased food intake would increase the risk of infection. Thus, the number of parasites could be used as an indirect biological marker for assessing the effectiveness of silver carp in filter-feeding on plankton. The following analysis indicated that silver carp with a body length of 50–55 cm showed the highest efficiency in controlling phytoplankton biomass. This study provides important information for understanding the ecology of C. schistorchis in wild silver carp.

Carassotrema schistorchis是双生寄生虫，其幼年和成年阶段寄生于定殖寄主鱼的肠道。没有关于野生寄主鱼中这种寄生虫感染的可用生态学信息。本工作旨在探讨的感染率和分布C. schistorchis野生鲢，鲢，并且由寄生虫评估对感染的环境因素的影响。从2016年10月到2019年5月，从两个水库中共采集了554只野生silver鱼。称重，测量和解剖这些收集的鱼，以观察血吸虫的存在遵循标准方法。生态学分析结果表明，寄主中血吸虫的频率分布呈聚集分布。丰富的C. schistorchis与silver的寄主年龄和条件因子呈正相关，但与水温，pH或DO无关。被感染鱼的条件因子值显着高于未感染鱼。这些结果表明食物摄入量而非环境因素直接决定了宿主体内寄生虫的感染，表明食物摄入量的增加将增加感染的风险。因此，寄生虫的数量可以用作评估biological鱼滤食性浮游生物有效性的间接生物学标记。以下分析表明，a鱼的体长为50-55厘米，在控制浮游植物生物量方面显示出最高的效率。这项研究为了解of的生态学提供了重要信息。野生silver鱼中的C. schistorchis。