In the context of increasing environmental contamination, our study employed fish as bioindicators, focusing on non-invasive cortisol measurements in scales and fins in response to severe PFAS pollution in the Veneto area of Italy. Our preliminary findings showed species-specific stress responses, as observed in Squalius cephalus and Padogobius bonelli, suggesting the need for broader biomonitoring to capture the complex impact of environmental stressors on aquatic organisms. Moreover, due to the unusual characteristics of the rivers selected for the biomonitoring activity, a possible link between PFAS exposure and cortisol levels in S. cephalus demonstrates the method's potential.