Hexamitosis is invasion disease of artificially grown salmonides. This fish disease occurs also to eelpouts and starlet. Pathogen of this fish disease is caused by flatworms hexamita (octoniiles) salmonis – small parasite of the dimension 7-12.5X3-8 mkm. Flatworm can produce cysts of the dimension 7-10 mkm that go out of the organism of the host. Infection of fishes occurs in the process of swallowing of the aforesaid cysts during feeding or with water. All species of salmonides fall ill with he