Predation of Cyclopoid Copepods on the Theronts of Ichthyophthirius multifiliis: Shedding Light on Biocontrol of White Spot Disease

White spot disease, caused by the parasitic ciliate Ichthyophthirius multifiliis, is a significant threat to freshwater fish farming industry worldwide, resulting in massive mortality and economic losses. Eliminating free-swimming theronts from culture environment considered crucial for control of I. multifiliis infection. It well-documented that planktonic ciliates are valuable food resources macro-zooplankton aquatic ecosystems. In this study, we developed fluorescence labeling method alive found cyclopoid copepods Thermocyclops taihokuensis, Mesocyclops spp., Macrocyclops sp., Paracyclopina sp. present predation on co-culture experiments. Laboratory challenge tests further confirmed presence zooplankton water body significantly reduced infection goldfish (p < 0.01). Results study revealed have potential be used as biological agents against white disease aquaculture.