This investigation was conducted in Doroudzan Dam located in Fars province from winter 2017 to summer 2018. The fish specimens were caught using monofilament gillnet with 20, 70, 100 and 120 mm mesh sizes. Overall, 283 fish specimens belong to the Cyprinidae (7 species) and Mugilidae families (1 species) were caught which were included: Cyprinus carpio, Carassius gibelio, Hypophthalmichthys molitrix, Hypophthalmichthys nobilis, Alburnus mossulensis, Capoeta damascina, Carasobarbus luteus and Planiliza abu. C. carpio and P. abu were dominant species during sampling seasons.The highest range of total length and weight belonged to H. nobilis (Length range: 52.8-102.6 cm; Weight range: 2811.5-20628.9 g) and the lowest ranges belonged to A. mossulensis (Length range: 8.6-15.1 cm; Weight range: 5.05-29.4 g) and P. abu (Length range: 8.3-19.6 cm; Weight range: 4.52-59.48 g). The highest amounts of the Shannon-Wiener and Simpson indices were observed in spring (2.413) and winter (0.795), respectively. PCA result showed that C. carpio and P. abu were the most effective species that caused the changes in the seasonal fish abundance and diversity. Also, the most amounts of seasonal similarity were between summer and spring (J= 0.625; S= 0.729) and the lowest amounts were between summer and winter (J= 0.375; S= 0.545).