In this study, reproductive characteristics of 485 specimens (240 males and 245 females) of Isfahan tooth-carp ( Aphanius isfahanensis ), one of the endemic species of Cyprinodontidae family in Zayandehrud River, with monthly sampling from June 2016 to May 2017, were studied. Sampling was performed in Zayandehrud River using a hand net (Sacchus). Male and female ages were between 0 + to 2 + years. The sex ratio was 1M:1.2F. The most frequent age group was 1 + in males and females. The highest value of condition factor was observed in July and was significantly different from those of other months. The highest value of condition factor was observed in July for females and was significantly different from those of other months, except June. The minimum, maximum and average absolute fecundity, were 7, 250 and 120±47(SD), respectively. The value of GSI in males was the highest in June and July (3.50) and (3.77), and this two months were not significantly different (P 0.05). Changes in liver index (HSI) in females during vitellogenesis in breeding seasons were high and its highest value was in June (6.43), and was significantly different from those of other months (P 0.05). According to the gonadosomatic index (GSI), egg diameter, monthly distribution of different stages of ovarian maturation, it was determined that the fish spawning peaks is in May and June. The long spawning season indicated that this fish is asynchronous spawner. Keywords : Isfahan tooth-carp, Aphanius isfahanensis , Zayandeh rood, Reproduction characteristics