Gelatine, a widely used product in food, pharmaceuticals, paper production, and photography, has safe applications but poses environmental risks due to its intermediate by-products, ossein and dicalcium phosphate. Improper disposal practices by some gelatine production facilities release these pollutants into aquatic environments, creating serious ecological concerns. This study investigates the histopathological and biochemical effects of ossein and dicalcium phosphate on the liver and muscle tissues of the freshwater fish Oreochromis mossambicus. Ossein and dicalcium phosphate, prepared from bone powder, were introduced to the water of the experimental tanks for nine consecutive days. Key water quality parameters (salinity, dissolved oxygen, dissolved CO?, and pH) were monitored in both groups. After exposure, liver and muscle tissues were analyzed for histopathological and biochemical changes. Histological examinations using hematoxylin and eosin staining revealed significant necrosis and disorganization of hepatocytes, while histochemical analyses indicated protein degradation. Biochemical assessments demonstrated increased glucose levels in muscle tissues, suggesting a compromised glycolytic process. Collectively, these changes resulted in abnormal behavior, homeostatic imbalances, reduced mobility, and eventual mortality in both ossein and dicalcium phosphate exposure groups. Bioaccumulation adds another layer of concern, amplifying the ecological threat. Addressing this issue requires enforceable regulations and sustainable waste treatment methods to safeguard aquatic ecosystems.