Gill histopathology in cultured sea bass (Dicentrarchus labrax (L.) coinfected by Diplectanum aequans (Wagener, 1857) and Lernanthropus kroyeri (van Beneden, 1851)

Because of a 1.5% daily mortality was recorded in sea bass (Dicentrarchus labrax) reared in floating-cage farm in Aegean Sea coast of Turkey, 15 sea bass were examined parasitologically and pathologically, in March 2010. Diplectanum aequans (Wagener, 1857) and Lernanthropus kroyeri (van Beneden, 1851) were detected in all fish. Of the 15 sea bass dissected, 100% were infected by Diplectanum aequans (Wagener, 1857), and mean intensity of infection was 31.9, 100% were infected by Lernanthropus kroyeri (van Beneden, 1851) and mean intensity of infection was 11.4, respectively. In the pathological examination of the gills, anemia, whitish mucuoid exudate and greenish egg sac belong to female Lernanthropus were observed. Histologic examinations indicated, both Diplectanum aequans and Lernanthropus kroyeri were present on branchial lamellae in the gills of all fishes. Lamellary edema formation, fusion of the secondary lamellae and necrosis in both primary and secondary lamellae due to parasitic irritation were determined. As a result, it was concluded that fish deaths were occurred due to the lesions formed after dense infestations of Diplectanum aequans and Lernanthropus kroyeri.