Cultivation of fish ciliate parasites: Progress and prospects

Ciliates are considered the most harmful parasites of fish, causing mass mortalities and thus substantial economic losses to the aquaculture and ornamental fish industries. To better elucidate their pathogenic mechanisms and facilitate the development of effective prevention and control strategies, it is essential to apply novel technologies to ensure the continuous and sufficient supply of parasite specimens. This review discusses the latest research progress in the artificial culture of six important parasitic ciliates affecting both freshwater and marine fish globally: Ichthyophthirius multifiliis, Cryptocaryon irritans, Chilodonella (C. hexasticha, C. piscicolaand C. uncinata), Balantidium ctenopharyngodoni, Scuticociliatida gen. spp., and Tetrahymena spp. Methods for in vitro and in vivo culture as well as cryopreservation/preservation (depending on the specific species) of these organisms are described herein. Challenges and future applications of parasite culture are also discussed.