Cryptocaryon irritans (Brown, 1951) is a serious threat to aquaculture of marine fish

Abstract

Cryptocaryon irritans (Brown, 1951) is a ciliated protozoan that was first described by Sikama, 1 who reported that it infected more than 45 fish species reared in marine aquaria. It was later renamed Ichthyophthirius marinus based on its cellular morphology, which is very similar to that of I. multifiliis, a parasitic ciliate of freshwater fish. 2 However, in 1951, Brown 3 re-described this parasite, which was found in imported fish, and named it C. irritans. This name is still in use today.

Severe Natural Outbreak of Cryptocaryon irritans in Gilthead Seabream Produces Leukocyte Mobilization and Innate Immunity at the Gill Tissue

“…Thus, once mortalities appeared, no survivors remained 8 days later. We used a group of fish from the same batch of hatched eggs (same age) located in other tank with a controlled temperature at 20 • C as a control group to guarantee the non-infection status, as C irritans infects when temperatures are over 20 • C [3,5,10]. Although the difference in temperature between the infected and control fish might alter the data, we decided to use this control since other possible controls for a natural outbreak such as the use of fish of different sizes or those who were asymptomatic from the same tank could also alter the data and would present limitations.…”

“…C. irritans is a holotrich ciliate protozoan that causes marine white spot disease or "marine ich" [4] and is considered to be the most devastating parasitic disease in both mariculture and in ornamental fish, commonly occurring when temperatures are above 19 • C, mainly between 20-30 • C, and generally between June and October [3,[5][6][7][8][9][10]. C. irritans exhibits very low host specificity and is able to infect multiple fish species, with gilthead seabream being the most affected amongst the cultured species in the Mediterranean area [10]. C. irritans invades fish epithelium of the skin, gills, and eyes, altering their physiological functions [3,5,11].…”

“…In fact, in China, natural outbreaks of C. irritans are quite frequent, causing an estimated USD 100 million in economic losses annually [10]. Natural outbreaks of C. irritans have been described in all continents [10], and it is known these outbreaks have a significant impact though their quantification in the aquaculture sector economy worldwide remains unknown. Therefore, knowledge of fish immune response against parasites is crucial to overcome this problem.…”

A decision support tool for parasite management in fish aquaculture

“…Innovation in parasite prevention benefits from deep knowledge of biology and behaviour of both fish hosts and parasites 1–7 . Yet, the fish aquaculture industry continues to have to rely to a large extent on medicinal baths or osmotic shift to treat ectoparasitic protozoans, flatworms and sea‐lice 8–12 . Medicinal baths are more effective if they are applied when parasite infection intensities are low and when they are timed to interrupt parasite life cycles (i.e., treatment intervals or therapeutic windows).…”

“…treat ectoparasitic protozoans, flatworms and sea-lice. [8][9][10][11][12] Medicinal baths are more effective if they are applied when parasite infection intensities are low and when they are timed to interrupt parasite life cycles (i.e., treatment intervals or therapeutic windows). Repeated use of chemotherapeutants drives the development of resistance in ectoparasites given their high fecundity and short life cycles, 13 thus strategically timed treatments are important because they alleviate treatment frequency and limit the amount of chemicals permeating into surrounding ecosystems.…”