This study aimed to investigate a case of acute vibriosis associated with Splendidus clade members in cultured European sea bass (Dicentrarchus labrax) from the Aegean Region of Turkey. Moribund fish (150-250 g) had lesions on their skin that ranged from small patches to shallow haemorrhagic ulcers and fin rot. Gram-negative bacteria were isolated from the liver, kidney, and spleen of affected fish and through 16S rRNA gene sequencing these isolates were identified as Vibrio pomeroyi, Vibrio crassostreae, Vibrio sp., and Vibrio anguillarum. V. anguillarum was isolated from only one examined fish, the bacterium seems less important to this case of vibriosis than the other identified vibrio species. All isolates were susceptible to flumequine, kanamycin, oxytetracycline, florphenicol and enrofloxacine. Oval shaped Amyloodinium spp. on the skin and Diplectanum aquans among the secondary lamellae of gills were determined as secondary pathogens. Parasitical asphyxia, epithelial cells hyperplasia in the gills was observed in addition to typical histopathological findings associated with Vibriosis. In this study, V. crassostreae and V. pomeroyi have been reported for the first time in Turkey as a fish pathogen.