Objective This study aimed to develop a visual active film using the inherent anthocyanins in purple yam as a natural indicator and its rich content of starch, polysaccharides, and proteins as the film-forming matrix, providing an intuitive and effective new approach for quality control of fish products.Methods Purple yam was processed by raw, steamed, and boiled treatments, then freeze-dried to obtain three types of purple yam powders, which were used to prepare visual active films corresponding to each treatment method. The effects of different citric acid additions on film properties were investigated. Based on comprehensive analysis of film characteristics, the optimal active film was selected and applied for real-time monitoring of fish freshness during 48 hours of storage at 25 ℃. The indicator effect was verified by analyzing the correlation between film color change and freshness indicators.Results The three types of purple yam powders exhibited different properties. The boiled yam powder had total phenolic and total anthocyanin content of 3.34 mg/g and 0.64 mg/kg, respectively. The film prepared from boiled yam powder with 1.00 g of citric acid showed a color difference value of 17.65, a moisture content of 12.25%, and an elongation at break of 56.66%. Films prepared from steamed and boiled yam powders showed significant color changes in response to ammonia gas and buffer solutions with pH values ranging from 1.0 to 14.0, indicating rapid responsiveness to volatile amines generated during fish spoilage.Conclusion Films prepared from steamed and boiled purple yam powders demonstrated a wider range of color expression. The addition of citric acid altered the color response range of the films. Throughout the storage period of fish, the color change of the visual active film was closely correlated with the degree of fish spoilage. By optimizing the cooking method of purple yam and adjusting the amount of citric acid added, a visual active film suitable for real-time monitoring of fish freshness can be effectively developed.