Cryptocaryon irritans, a ciliate parasite of an ornamental reef fish yellowtail tang Zebrasoma xanthurum

Abstract Cryptocaryon irritans is an obligate parasitic ciliate protozoan of wild and cultured marine fish. It causes white spot disease, and infections with this pathogen can cause significant losses for aquarists and commercial marine cultures worldwide. This study reports the occurrence of C. irritans parasitizing the ornamental reef fish, yellowtail tang, Zebrasoma xanthurum. Six days after being introduced to a new environment, 11 yellowtail tangs had white spots scattered across their bodies and fins. Suspicion of infection with C. irritans was evaluated by scraping the skin to confirm clinical diagnosis. After confirmation, the yellowtail tangs were transferred to a hospital aquarium and treated with the therapeutic agent Seachem Cupramine® for 15 days. During the treatment period, the copper concentration was monitored daily. At the end of the treatment, none of the yellowtail tangs showed clinical signs of white spots on their bodies, and skin scraping confirmed the yellowtail tangs were no longer infected. Subsequently, the yellowtail tangs were released for sale.