Discus (Symphysodon spp.) are costly and prized specimens in the international ornamental fish trade. The majority of discus submitted to the Aquatic Animal Health Unit at the University of the West Indies School of Veterinary Medicine for necropsy between September 2010 and September 2015 had lesions consistent with Cryptobia iubilans infection, thus prompting this study. To determine the prevalence of the flagellated gastrointestinal protozoan C. iubilans in discus fish, 32 discus were sourced from 10 suppliers, including breeders, importers, and hobbyists across Trinidad. Fish were euthanized, and the internal organs, particularly the stomach and intestine, were observed under a light microscope for characteristic granulomatous lesions and/or live C. iubilans parasites. All wet-mount slides on which granulomas were observed were also Ziehl-Neelsen acid-fast stained to presumptively exclude the presence of Mycobacterium spp., the main differential when diagnosing C. iubilans–associated granulomatous gastritis or to determine the presence of dual infections. Further histological analyses were performed on stomach and intestinal sections, and transmission electron microscopy was used to confirm the parasite in stomach sections. The prevalence of C. iubilans infection was found to be 81.3%, and the prevalence of presumptive dual infections with Mycobacterium spp. was found to be 21.9%. To the best of our knowledge, this is the first documented study of C. iubilans infections in the wider Caribbean region.

铁饼（Symphysodon spp。）是国际观赏鱼贸易中昂贵且珍贵的标本。在2010年9月至2015年9月之间，因尸检而提交至西印度群岛大学兽医学院水生动物卫生部门的大部分铁饼的病灶均与Cryptobia iubilans感染一致，因此推动了这项研究。为了确定铁饼鱼中带鞭毛的消化道原生动物C. iubilans的患病率，从特立尼达的十个供应商（包括育种者，进口商和业余爱好者）采购了32个铁饼。对鱼实施安乐死，并在光学显微镜下观察内部器官，特别是胃和肠的肉芽肿特征性病变和/或活体C. iubilans寄生虫。所有观察到肉芽肿的湿载玻片也进行了Ziehl-Neelsen耐酸染色，以推测排除分枝杆菌的存在，而分枝杆菌是诊断C. iubilans相关肉芽肿性胃炎或确定双重感染的主要区别。对胃和肠段进行了进一步的组织学分析，并使用透射电子显微镜确认了胃段中的寄生虫。患病率C. iubilans感染被认为是81.3％，和推定双重感染与患病率结核分枝杆菌。被发现是21.9％。据我们所知，这是关于加勒比海地区的C. iubilans感染。