Oil-contaminated water is now a serious environmental issue caused by a variety of industries and manufacturing processes. Because of its toxicity, it endangers both the environment and other living things. Most methods for treating oily water and removing oil from water are time-consuming, expensive, need a large number of staff and equipment, and, in most cases, cause environmental damage. Adsorbents have gained popularity among available approaches in recent years due to their ease of use and low cost. The present research focuses on the possibilities of using fish scales as low-cost adsorbents for oil adsorption in water via batch processing. Fish scales were cleaned with water, dried in sunlight, and then heated in an oven at 70 °C for 1 hour before being carefully ground. The samples were passed through a 60-200-mesh sieve (74-250 mm). The materials were characterized using X-ray diffraction (XRD), X-ray fluorescence (XRF), and scanning electron microscopy (SEM). Response surface methodology (RSM) was employed to investigate the effect of different experimental conditions on oil adsorption. To achieve the highest engine oil adsorption capacity of 90.04 mL, the following parameters were optimized: adsorption time of 33.17 minutes, agitation speed of 203.19 rpm, and adsorbent weight of 19.74 g. As a result, fish scales are a promising and environmentally benign biosorption material for the removal of contaminants from natural and wastewater sources.