Fish provides high-quality protein, omega-3 fatty acids, and essential vitamins and minerals crucial for human health. This study evaluated the effects of seasonal variation and processing methods on the proximate and mineral composition, and fat quality of L. gossei fish species from Lake Malawi, using the AOAC and Wijis’ methods for iodine value (IV) determination. Results from one-way ANOVA revealed the highest ash (18.72±1.20%) and protein (12.62±0.21%) levels during the hot-dry season. Fat content (FC) was highest during the rainy season (28.80±2.01%) and the hot-dry season (27.87±3.23%). However, the cold season exhibited significantly lower FC (12.17±2.02%). The IV was higher in hot-dry season (238.48±2.36 gl2/100 g) compared to cold (153.62±3.21 gl2/100g) and rainy seasons (165.01±2.30 gl2/100 g). Female L. gossei had highest fat (36.08±0.20%) and polyunsaturated fatty acids (259.91±0.10gl2/100g) than males during rainy and hot-dry seasons. Mineral content was also highest in the hot-dry season. Processing methods like solar drying increased ash (20.98±2.81%) and fat content (27.50±8.62%) while smoking increased protein content (33.60±2.02%) than boiling and solar drying. However, boiling and solar-drying significantly increased IV (182.67±3.90 gl2/100g) and (164.32±3.50 gl2/100g) respectively, compared to smoking (144.95±2.01gl2/100g). Therefore, L. gossei is most nutritious when harvested in the hot-dry and rainy seasons, with solar drying retaining minerals and IV, and smoking enhancing protein content.