Fuente: Grasas y Aceites This study investigates seasonal variations in total lipid content and fatty acid composition of five fish species (Capoeta trutta, Capoeta umbla, Carasobarbus luteus, Carassius gibelio, and Cyprinus carpio) from Dicle Dam Lake, Diyarbakır, in the Mesopotamian River system. C. gibelio exhibited the highest total lipid values, with percentages of 7.57% in winter, 8.55% in summer, and 8.30% in autumn. In C. trutta, SSFA peaked in autumn (38.64%), mainly due to C16:0 (27.08%), and SPUFA was the highest in winter (38.31%), with major contributors being EPA (12.21%) and C18:2ω6 (10.85%). C. umbla had peak SSFA in autumn (31.27%) and SPUFA in winter (43.06%), driven by C18:2ω6 (19.14%) and EPA (9.27%). Both C. trutta and C. umbla had maximum SMUFA in summer, mainly from C18:1ω9. C. luteus showed high SPUFA in autumn (48.88%) and summer (48.30%), with DHA C22:6ω3 reaching 16.69% in summer. C. gibelio had peak SPUFA in winter (49.89%) and summer (49.33%). C. umbla had the highest Sω3/Sω6 ratio in spring (2.04). Seasonal variations in fatty acid composition reflect the dynamic lipid profiles of these commercially important fish, offering insights into their nutritional quality and guiding seasonal dietary recommendations.