Antimicrobial activity of Leucas aspera engineered silver nanoparticles against Aeromonas hydrophila in infected Catla catla

•Biosynthesis of silver nanoparticles (AgNPs) by bark extract of Leucas aspera.•Characterization of AgNPs by UV–vis, TEM and FTIR analysis•Analysis of antibacterial activity in vivo in Cutla cutla fish model. This research describes green synthesis of silver nanoparticles (AgNPs) utilizing Leucas aspera. The synthesized nanoparticles were characterized by UV–visible spectroscopy (UV–vis), dynamic light scattering (DLS), transmission electron microscopy (TEM), Fourier transform infra-red spectroscopy (FTIR) and inductively coupled plasmon optical emission spectroscopy (ICP-OES). UV–vis analysis proved the wavelength of the sample to be 429nm, resembling the surface resonance peak (SPR) specific for AgNPs. DLS analysis indicated particles with superior stability with an average diameter of 189.3nm. TEM results showed that the particles were in the size range of 29–45nm. FTIR prediction indicated the presence of possible polyphenol and protein encapsulates on the AgNPs. Antimicrobial activity of the AgNPs was tested against Aeromonas hydrophila. Catla catla, the model organism used for the experiment was divided into six groups with 15 animals in each group. In vivo analysis of biochemical parameters and histological architecture provided evidence for the antibacterial effect of AgNPs in the fish model.