Infection of Aphanius sophiae (Heckel, 1849) (Actinoptrygii: Cyprinodontidae) with Tetracotyle sp. in Cheshmeh-Ali Damghan, Semnan Province, North of Iran

During the study on the biology of Aphanius sophiae, a total of 20 fish specimens were collected in September 2007 using dip net at a depth of 30 - 50 cm in downstream of spring and preserved them in 10 % formalin in spot until examination. The fish were dissected and the ear cavity was examined to determine the presence of parasites of which 4 specimens including 4 females were infected with Tetracotyle sp. metacercariae, a trematode which in its metacercarial stage may infect a wide range of freshwater fish species. These metacercariae were positioned into cavity of inner ear membrane of infected fish. Our data showed that the infection was higher in females than males also as the number of parasites increases in fish ear, the size of parasites decreases. The prevalence of the infection with Tetracotyle sp. was 20 %, the parasite intensity was 2.5 and the parasite abundance was 0.5 in A. sophiae. Cercariae of Tetracotyle sp. infect fish by direct penetration. Two fish were infected with 3 parasites and other fish had 2 parasites in their ears, separately. This shows that even the inner ear is not exempted from the attacks of trematodes. This is the first report of Aphanius sophiae infection with Tetracotyle sp. metacercariae.