Vibrio parahaemolyticus is one of the causes of acute hepatopancreatic necrosis disease or early mortality syndrome
in shrimps. Frequent and repeated application of antibiotics leads to generating resistant strains. Bacteriophages
and plant extracts are considered potential biological agents in precaution and treatment of bacterial diseases in
aquaculture. The study aimed to investigate the effects of bacteriophages and Phyllanthus amarus extract on strains
of V. parahaemolyticus bacteria that were isolated from white leg shrimps (Litopenaeus vannamei). In this study, two
strains of V. parahaemolyticus were used: B4XT4 (pure strain) and B4X0T2.2 (isolated strain) for preparing four
treatments consisting of combining the bacteria with P. amarus extracts (8 mg/mL), bacteriophage (106 PFU/mL), a
combination of P. amarus and bacteriophage, and a control treatment. The experiment was conducted in triplicate.
The results showed that only plant extracts could inhibit bacterial growth. The colonial morphology of bacteria was
changed when bacteriophages and P. amarus extract were added.