Identification of Some Bacterial Infections in Nile Tilapia (Oreochromis niloticus) Cultured in Bafgh Fishery Research Center

Tilapia is one of the important farmed fish in the world. In the recent years this fish has been grown for evaluating the possibility of farming in climate status of Bafgh region. The aim of this study was identification of some important bacterial pathogens in farmed tilapia. In this study thirty fish with 153.4 g (average weight) and 20.12 cm (average length) were randomly collected from ponds. Some bacteriological and biochemical tests such as gram staining, Catalase, H2S production, Indole and motility were used. For definitive identification of isolates, PCR test was done by use of special paired primers. For each bacterium a target gene is detected. From two bacterial groups, gram positive and gram negative, six species were identified. In the gram positive group, Lactococcus graviaea and in the gram negative group, Yersinia ruckeri, Aeromonas hydrophila, Vibrio alginoliticus, V. parahemoliticus and V. vulnificus were identified. Understanding of different bacterial agents in the fish farm environments is essential for cultivation of tilapia. There are different bacterial agents, each of which can be considered to threaten the living conditions of fish. Respecting the health management leads to increasing fish immunity and helps their survival in the cultivation status.