en fish disease fish disease پژوهشي Orginal research papers <span lang="TR" style="font-size:11.5pt"><span calibri="" style="font-family:"><span style="color:black">The Asian sea bass (<i>Lates calcarifer</i>), also known as barramundi, is a species of great importance in Iran&rsquo;s aquaculture industry. This fish has been farmed for many years to fulfill the rising domestic demand for fresh seafood and to promote exports.</span></span></span> <span lang="TR" style="font-size:11.5pt"><span calibri="" style="font-family:"><span style="color:black">However, bacterial diseases and infections pose a significant threat to the growth of this popular species, leading to substantial losses. This study aimed to investigate bacterial contamination in barramundi at coastal cage farms located in the Bushehr and Hormozgan provinces of Iran, as well as to identify the signs and lesions resulting from these infections. According to the criteria for bacterial infection, 30 fish samples were collected from farms. Necropsies were performed on the collected fish, followed by bacteriological analysis and genotyping using 16S rRNA sequencing. The bacteriological results revealed five bacterial strains, confirmed through agent isolation, biochemical profiling, and 16S rRNA sequence verification. </span></span></span><span lang="TR" style="font-size:11.5pt"><span calibri="" style="font-family:"><span style="color:black">The identified isolates comprised <i>Streptococcus iniae</i> strain SB1 (60%), <i>Streptococcus agalactiae</i> strain 20 (70%), <i>Shewanella</i> <i>algae</i> strain 16 (60%), and <i>Vibrio</i> species such as <i>V. azureus</i> strain N3 (86%) and <i>V. harveyi</i> strain N4 (90%).</span></span></span><span lang="TR" style="font-size:11.5pt"><span calibri="" style="font-family:"><span style="color:black"> The identification of bacterial species is crucial for resolving health issues and reducing mortality in farmed barramundi. This study comprehensively identified bacterial pathogens impacting barramundi in Iran. The findings, along with the detection methods and bacterial genotyping techniques used, offer practical insights for future research in this area. Additionally, this study increases awareness among researchers, farmers, and clinicians, facilitating the adoption of effective management strategies in aquaculture practices.</span></span></span><br> <span style="font-size:11pt"><span style="line-height:150%"><span style="font-family:Calibri,sans-serif"><span style="font-size:12.0pt"><span style="line-height:150%"><span style="font-family:"Times New Roman",serif"></span></span></span></span></span></span> Barramundi, Asian sea bass, 16S rRNA, Bacterial infection, Streptococcus iniae, Vibrio harveyi, Persian Gulf 245 258 http://jifro.ir/browse.php?a_code=A-10-4905-1&slc_lang=en&sid=1 S.M. Joghataei mehdi.joghataei@ut.ac.ir 100319475328460055147 100319475328460055147 No Department of Microbiology and Immunology, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran D. Nikaein dnikaein@ut.ac.ir 100319475328460055148 100319475328460055148 Yes Department of Microbiology and Immunology, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran A. Erfanmaensh erfanmanesh@acecr.ac.ir 100319475328460055149 100319475328460055149 No Research Group of Animal Biologic Products, Academic Center for Education, Culture, and Research (ACECR), Tehran Organization, Tehran, Iran M.S. Moradi 100319475328460055150 100319475328460055150 No Department of Animal and Poultry Health and Nutrition, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran