Linear Mixed-Effect Model (LME) of all detected fatty acids in visceral adipose tissue of European grayling (Thymallus thymallus), summed in classified FA groups (SFA, MUFA, PUFA and n-3 HUFA). These groups represent the FA content in the entire VAT (FA content * VAT weight). Throughout the monitored period, stocked fish exhibited a significant decrease in every FA group, starting from June and maintaining a consistent downward trend. By contrast, pond grayling did not display any pronounced variations in any FA group over time. The error bars represent 95% confidence intervals.