The present study is in vitro study to evaluate the antimicrobial activity of the ethanolic extracts derived from leaves of Ficus benjamina L. and its cultivars (Safari, Baroque, Amstel Gold, Reginald) against Aeromonas sobria to assess the possible use of this plant in preventing infections caused by this fish pathogen in aquaculture. Antimicrobial susceptibility of the tested Aeromonas sobria was performed by the Kirby-Bauer disc diffusion method according to the recommendations of the Clinical and Laboratory Standards Institute (CLSI). Our results revealed, that F. benjamina and its cultivars possessed antibacterial properties against Aeromonas sobria strain. The ethanolic extract obtained from leaves of F. benjamina ’Safari‘ exhibited the maximum antimicrobial activity against Aeromonas sobria (the mean of inhibition zone diameter was 26.19 ±1.32 mm). Aeromonas sobria strain was susceptible to the F. benjamina ’Amstel Gold‘ (15.25 ±1.25 mm) and ’Reginald‘ (16.25 ±1.10 mm). Aeromonas sobria strain was the most resistant to F. benjamina (12.5 ±0.80 mm) and F. benjamina ’Baroque‘ (13.63 ±0.75 mm) leaf extracts. The results of this study provide a new perspective for the use of various Ficus species as medicinal plants to improve the antibacterial responses in aquaculture. Scanning electron microscopy has been employed to observe epicuticular wax structures which can be used to assure the correct identification of plant raw materials. Further studies including the use of other medicinal plants as food additives in aquaculture, the assessment of their antioxidant effects on various tissues of salmonids are in progress.