Telogaster opisthorchis is an endoparasite in the class Trematoda within the phylum Platyhelminthes. This fluke is known for causing tumor like malformations in fishes (intermediate host) by attaching onto its spinal region in the metacercariae form. Malformations cause fish to become more susceptible to fish eating predators (definitive host) allowing T. opisthorchis to continue with its lifecycle.