Nerocila bivittata (Crustacea, Isopoda, Cymothoidae) is reported for the first time on the caudal peduncle of the Rusty blenny, Parablennius sanguinolentus (Teleostei, Perciformes, Blenniidae), collected from Samsun Coast, Black Sea, Turkey. N. bivittata parasitized 7.4% (2 of 27) of the P. sanguinolentus collected.