Antibacterial Efficacy of Mangroves: Using Bioactive Leaf Extracts of Avicennia officinalis to Combat Bacterial Diseases in Fish

Ghosh, S.; Pattanayak, R., and Pulapparambil, A., 2025. Antibacterial efficacy of mangroves: Using bioactive leaf extracts of Avicennia officinalis to combat bacterial diseases in fish. Journal of Coastal Research, 41(2), 305–313. Charlotte (North Carolina), ISSN 0749-0208. This study examines the practice of using bioactive extracts for fish health promotion and chronic therapy for better production with minimum environmental impact in sewage-fed aquaculture in East Kolkata Wetlands. Avicennia officinalis leaf extract is used as herbal medicine against freshwater fish bacterial disease under culture conditions. Biochemical and morphological identification tests were conducted on infected fishes collected from farmers' fields and farm culture ponds. The antibacterial activity, minimum inhibitory concentration, and disease treatment ability of leaf extracts were tested against three identified fish bacterial pathogens in vitro. The ethyl acetate leaf extract of A. officinalis showed better inhibition activity than other solvents at a concentration of 40 lg/mL against Aeromonas hydrophila and Aeromonas liquefaciens, and 80 lg/mL against Pseudomonas fluorescens in this in vitro assay. The experimental treatment results showed that the herbal feed with 8% leaf extract was more effective than the other two types of tested herbal feed containing 2% and 4% of A. officinalis leaf extract on the infected fishes. This can nurture immunity and decrease fish mortality against the tested bacterial isolates. This in vitro experimental study also showed the effectiveness of ethyl acetate leaf extract of A. officinalis as a feed additive in fish bacterial disease management as a sustainable substitute for synthetic antibiotics under culture conditions.