Agricultural Research,Education and Extension Organization Iranian Journal of Fisheries Sciences 1562-2916 25 4 2026 07 01 Isolation and identification of autochthonous potential probiotic candidates from the gastrointestinal tract of Caspian striped mullet (Mugil cephalus) 771 786 135972 10.22092/ijfs.2026.135972 EN F. Mahmooditabar Department of Food Hygiene, Faculty of Veterinary Medicine, Amol University of Special Modern Technologies, Amol, Iran M. Azizkhani Department of Food Hygiene, Faculty of Veterinary Medicine, Amol University of Special Modern Technologies, Amol, Iran R. Khoshbakht Department of Pathobiology, Faculty of Veterinary Medicine, Amol University of Special Modern Technologies, Amol, Iran P. Shohreh Department of Clinical Sciences, Faculty of Veterinary Medicine, Amol University of Special Modern Technologies, Amol, Iran Journal Article 2026 08 09 This study aimed to screen and identify potential probiotic strains from the gastrointestinal tract of Caspian striped mullet (<em>Mugil cephalus</em>). Eight out of forty isolates showed antibacterial activities against fish-associated pathogens: <em>Yersinia ruckeri</em>, <em>Salmonella</em> <em>enterica</em>, <em>Escherichia coli </em>O157:H7, and <em>Staphylococcus aureus</em>. Biochemical tests showed that 50% of the isolates were capable of glucose fermentation, 75% fermented arabinose, 37.5% and 62.5% were able to metabolize raffinose and mannitol, respectively. None of the eight isolates demonstrated the ability to ferment all tested sugars. The isolates demonstrated tolerance to a high bile concentration (4000 mg/L) as well as to mildly acidic and alkaline pH conditions. Three isolates exhibited100% sequence identity with <em>Carnobacterium maltaromaticum.</em> One of the isolates exhibited 99% sequence identity with <em>Carnobacterium divergens</em>. Two isolates exhibited 71% sequence identity with Weissella koreensis and other Weissella species. Sequencing analysis revealed that the fish gut isolates are closely related to lactic acid bacteria, particularly <em>C. maltaromaticum</em> and <em>C. divergens</em>. The results indicate that the isolates have potential as probiotics in aquaculture due to ability to enhance gut health and suppress pathogenic bacteria. https://jifro.areeo.ac.ir/article_135972_06185290149df67b1adc0c3615ed1b3f.pdf