DOI: 10.11648/j.ajset.20261104.22 ISSN: 2578-8353

Bacterial Diversity and Antimicrobial Resistance Profiles of Freshwater Fishes in Ganjam, Odisha

Padmabati Nayak, Sambit Dwibedy, Sushil Rathore, Namita Panigrahy
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Bacteria are essential components of aquatic ecosystems, performing critical ecological functions and influencing the health of their hosts. With aquaculture recognized as the fastest-growing food production sector, ensuring the bacteriological safety of freshwater fish is vital for ecological sustainability and human health. This study aimed to isolate, characterize, and identify the bacterial diversity associated with the skin, fins, gills, and gastrointestinal tracts of eight freshwater fish species, including Catla catla , Labeo rohita , and selected catfishes, collected from various water bodies of the Ganjam district, Odisha. Bacteriological profiling was conducted for isolation, morphological characterization, selective media, and biochemical identification, using standard microbiological methods. 72 bacterial isolates were recovered and subjected to antibiotic susceptibility testing using the Kirby–Bauer disc diffusion method against ten antibiotics from different classes, including carbapenems, beta-lactams and polymyxins. Quantitative analysis demonstrated that the highest bacterial load in the gut of Anabas testudineus (2.8 × 10 7 CFU/ml), followed by Labeo species. Gram-positive bacteria were found to be more prevalent than Gram-negative bacteria species. The identified genera included Gram positive bacteria, such as Bacillus , Lactobacillus , Staphylococcus , Streptococcus , and Micrococcus as well as Gram negative bacteria, such as Aeromonas , Pseudomonas , and Proteus , while Escherichia coli and Vibrio species were not detected. The antibiogram revealed significant resistance to ampicillin, penicillin-G, and colistin, whereas chloramphenicol remained effective against most isolates. These findings indicate the occurrence of antimicrobial-resistant bacteria in commercially important freshwater fishes and highlight the importance of rational use of antibiotics, improved aquaculture management, and stringent food safety measures to mitigate potential public health risks.

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