Ichthyophthirius

Ichthyophthirius is a genus of parasitic protozoans that cause "ich," a common disease in freshwater and aquarium fish. These organisms are a type of ciliate, characterized by their hair-like cilia used for movement and feeding.123

Ichthyophthirius multifiliis, the primary species, infects the skin and gills of fish, appearing as small white spots. Symptoms include scraping against objects, loss of appetite, and unusual hiding behavior. The parasite matures within the fish's skin, forming a cyst-like structure that protects it from water treatments. Immature forms, called tomites, are released from the cyst and must quickly find a new host to survive.1

While copper sulfate can be effective at certain life stages, developing an antiparasitic vaccine is challenging due to difficulties in laboratory cultivation and administration.1