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Acanthobrama urmianus is an endemic species of Cyprinidae family in the Urmia Lake basin and important for ecological and sport fishing. The main purpose of this study was to investigate the relationship between the fecundity with length, weight and age in two rivers of Mahabadchai and Siminerud and sampling was carried out from December to June using cast-net and gill-net. The result of the study on 107 female fish specimens from maturity stages 4 and 5 showed that the absolute fecundity of this fish is 1567 to 27228 (11954.3±6991.9) eggs with a diameter of 0.35 to 1.42 and the relative fecundity is 87.9 to 633.9 with an average of 282.6±120.7. Also, with increasing age and size of the fish body, the absolute fecundity increased. Between the absolute fecundity and the total length of equation F= .0034TL ^3.545 (r²=.789) and between the absolute fecundity and the weight of the equation F=23.272W^1.665 (r²=.766) obtained. The results showed that the rate of fecundity in Mahabadchai in the constant length range was less than Siminerud River.