Bacterial diseases have emerged as a significant issue within the fish ecosystem, and the use of antibiotics to treat these diseases has detrimental effects on both fish and the environment. Therefore, it is imperative to seek out natural products that are safe for combating fish diseases. This research aims to assess the antibacterial properties of an extract derived from Muntingia calabura against various bacteria, including A. hydrophila, A. salmonicida, E. ictaluri, P. aeruginosa, E. tarda, and V. alginolyticus. M. calabura extract was obtained by soaking with ethanol solvent. This extract has been tested for phytochemical content and characterized by FT-IR. The antibacterial activity of the M. calabura extract was evaluated using the agar diffusion method, employing concentrations of 100, 200, 300, 400, and 500 mg mL-1. The phytochemical analysis of the M. calabura extract revealed the presence of flavonoids, phenolic compounds, saponins, and terpenoids. The results of the FT-IR characterization of M. calabura extract contained O-H, C=O, C=C aliphatic, C=C aromatic and C-O groups. The inhibition tests demonstrated that the M. calabura extract effectively hindered the growth of A. hydrophila bacteria by a range of 8.1 mm to 14.2 mm, A. salmonicida by 9.2 mm to 10.9 mm, E. ictaluri by 8.8 mm to 11.5 mm, P. aeruginosa by 8.1 mm to 12.1 mm, E. tarda by 9.6 mm to 11.4 mm, and V. alginolyticus by 8.2 mm to 12.2 mm. In summary, the extract from M. calabura has the potential to effectively on paper plates and incubated at 30°C for 24 hours.