Microplastic pollution has gained global attention due to its toxic impact, particularly on aquatic organisms. As an omnivorous species, tilapia is susceptible to microplastic (MP) exposure in water. This study analyzed the oxygen consumption rate and histology of systemic organs in tilapia exposed to microplastics. An experimental method with a completely randomized design (CRD) was employed in 12 aquariums (40L) equipped with aeration. There were four treatment groups for MP exposure, each with three replicates: concentrations of 1, 10, 100mg/ L, and a control group without MP. The microplastics used were polyethylene particles sourced from soaked plastic bottles collected over 30 days in the Tello River, Makassar. The assessed parameters included oxygen consumption rate and tissue alterations. Data were statistically analyzed using one-way ANOVA for oxygen consumption, while tissue alterations were described qualitatively. The results indicated that the highest oxygen consumption rate occurred at the 10mg/ L treatment (P<0.05), followed by the 1 and 100mg/ L treatments, with the control group showing the lowest rate. Histological tests revealed alterations, including thinning of the interlamella, fractures and swelling of the secondary lamella, and shrinkage of mucus cells in the gills. In the intestines, alterations included thickening of the muscular and serosa layers. The study concluded that MP exposure significantly affects the oxygen consumption rate, particularly at a concentration of 10mg/ L. Additionally, histological alterations were observed in tilapia exposed to microplastics, with the most severe changes occurring in the gills at a concentration of 100mg/ L.