In this study the infection status of swimbladder nematode Anguillicoloides crassus in European eel (Anguilla anguilla) was evaluated for the northeast Mediterranean Region of Turkey. 170 fresh European eel samples were obtained from the four different river side fish markets (whilst processing stage) as follows 45 from Goksu River (G), 42 from Seyhan River (S), 42 from Ceyhan River (C), and 41 from Asi River (A) in two times during a period of 3 years. The number of infected eels (Ni), prevalence (P%), parasite abundance (A), and mean intensity (MI) values were calculated according to the sampled period/locations. The
prevalence, parasite abundance, and mean intensity values of parasites were higher Asi River than others.