This study aimed to compare the morphological characteristics of Salmo Trutta Fario populations inhabiting three distinct regions: the Lar Dam Basin in Tehran Province (Jajrod), the Kileh Spring River in Mazandaran Province (Tonekabon), and the Gorgan River in Gilan Province (Talesh). A total of 90 individuals were sampled for morphometric analysis. Ten traits were assessed using both traditional morphometric and geometric morphometric techniques. The findings demonstrated significant differences (p < 0.05) in morphological traits among the three populations, with geometric morphometric revealing distinct separation of the Lar Dam Basin Hatchery population from the others. The utilization of both methods proved effective in delineating population variations within the Salmo Trutta Fario species. Cluster Analysis Dendrogram further underscored the presence of an independent population within the studied regions. This research provides valuable insights into the morphological diversity of Salmo Trutta Fario populations, contributing essential information for fisheries management and conservation strategies.