This ciliates falls under the phylm ciliophora because it is an alveolate and has cortical alveoli (a layer of small, bubble-like, membrane supporters). The Alveolata is a monophyletic group of primarily single celled eukaryotes (cilliates, dinoflagellates, apicomplexans). It is also known as the "Ick" parasite of fish. It penetrates the skin of fish and after the fish dies the parasite is able to infect other fish in the area.
The tomite is the immature stage of the parastie that is produced in numerous quantities in the cyst and then released to infect other fish. The tomite penetrates the skin of the fish where it then grows into an adult trophont. A white pustules (visibly cysts) are formed along the skin of the fish and eventually the fish becomes ill and dies.
The young infective tomite enters the skin of the fish and froms a pustule. In the pustule, it then grows into an adult trophont, which is the active feeding stage in the parasite's life cycle. When the fish dies, the trophont leaves the pustule and becomes a non-feeding tomont. The tomont settles to the bottom of the tank and encysts. The cyst ultiplies by binary fission and when the cyst wall breaks young infective tomites are released and can find other fish to infect.