[Surgical removal of a follicular carcinoma of the thyroid gland in a snakehead (Channa barca, HAMILTON, 1822)].

Inflammatory processes, neoplastic growths or rare dysontogenetic malformations may cause mass formation in the gills of fish. In the present case, a follicular carcinoma of the thyroid gland in a Barca snakehead and its surgical removal are reported, and neoplasms in fish are discussed. Following clinical, radiological, cytological and sonographic examinations, the gill-associated partly cystic mass was incompletely removed surgically. The subsequent histological examination identified the mass partly as a follicular carcinoma of the thyroid gland. Because the main alterations of the surgical specimen were non-neoplastic, the development from a rare preexisting hamartoma is discussed. No bacteriological or mycological secondary infections were identified. This report is the first description of a follicular carcinoma and its surgical removal in a snakehead.