Tachaea chinensisis an ectoparasite commonly found on diverse ecologically and commercially valuable freshwater shrimps and prawns. Previous studies on this parasite have focused on its distribution and taxonomical identification, while its host preference and/or the potential predation in this host-parasite interaction remained poorly understood. In this study, we investigate the host preference and potential predation of the isopodT. chinensisusing manipulative choice and predation experiments under laboratory settings. The preference toward a broad range of host decapods in single-host treatments, indicates a low host specificity, which ultimately aids in the survival of this parasite in the natural environment.Tachaea chinensisresponded well to the shrimpPalaemon paucidenswhen presented with uncommon host species in all three treatments. In host-parasite predation treatments, all the testedP. paucidensshrimp, the prawnMacrobrachium nipponense, and the crayfishProcambarus clarkiiwere able to consume the isopod–especially the invasive crayfishP. clarkii, which consumed a greater percentage in a considerably shorter time frame (Fisher's exact test,P< 0.01). This study demonstrated for the first time the ability of larger freshwater decapods to prey uponT. chinensis. Despite the large difference in the maximum attainable size of those freshwater species, a high predation pressure by the invasive crayfish on the isopod is anticipated, if they are present in the same environment.