An immature female of the cymothoid isopod, Ceratothoa verrucosa (Schioedte and Meinert, 1883), was found to be attached ventrally to the roof of the buccal cavity of a red seabream, Pagrus major (Temminck and Schlegel, 1843), cultured in Kamisakiura Cove, Mie Prefecture, central Japan, in July 2008. Since April 1985, data on the diseases of marine fishes cultured in this prefecture have been taken at two prefectural organizations, but only two records of C. verrucosa infection, including the present case, were found in those long-term data from an examination of more than 14,591 farmed red seabream from April 1985 to July 2017. This indicates that C. verrucosa is an extremely rare parasite of farmed red seabream in Mie Prefecture.