the effect of plant extracts prosopis farcta, datura stramunium and calotropis procera against three species of fish pathogenic bacteria

background: the repetitive use of antibiotics in different fields (veterinary and medicine) improves the emergence and occurrence of the resistance phenomenon in pathogenic bacteria. due to the problem of antimicrobial resistance, it is an urgent need to discover new drugs and alternative treatments for the control of bacterial diseases in aquaculture. objectives: the purpose of this study is to investigate antibacterial effects of methanol and hexane extracts of medicinal plants rattles (prosopis farcta), datura (datura stramunium l) and milkweed (calotropis procera l), the major pathogenic bacteria of fish, including aeromonas hydrophila, yersinia ruckeri and streptococcus iniae. methods: extraction was performed using a rotary evaporator. to determine the minimum inhibitory concentration (mic), the standard microdilution method (dilution in broth) was used and the minimum bactericidal concentration (mbc) was determined based on mic values obtained for each extract. results: the results showed that the effect of most potent extract, methanol extract obtained from fruit rattle on the three studied bacteria, with mic and mbc are 25, 50mg/ml, respectively. the most sensitive bacteria to methanol and hexane plant extracts, is bacterium streptococcus iniae and aeromonas hydrophila and yersiniaruckeri bacteria were resistant. the studied extracts had stronger antibacterial properties against gram-positive bacteria compared to gram-negative. conclusions: according to the results, it seems that the use of methanol extract of prosopis farcta fruit is effective for treatment of bacterial diseases in aquaculture.