Protozoal parasites can be divided into Ciliates and Flagellates.

Common ciliated parasites that affect pet fish include Ich, Chilodonella, Trichodina, Tetrahymena and others

Click on the links below to learn more about these parasites
 

ICH

Chilodonella

Trichodina

Tetrahymena

Common flagellated parasites of tropical fish include Ichthyobodo (Costia), Hexamitids, and Cryptobia.  Click on the links below to learn more about these parasites.

Ichthyobodo (formerly Costia)

Hexamitids (Hexamita/Sprinucleus)

Cryptobia