The life-history traits of Aphanius danfordii in Hirfanlı Reservoir were studied on the basis of 2252 specimens caught between April 2008 and April 2009. Maximum age was determined as five years for both sexes. The overall sex ratio of males to females was 1 : 1.21; however, this ratio varied by age and season. Mean total length at age data derived from scale readings were used to estimate growth. The von Bertalanffy growth parameters were: L∞ = 126.63 mm, K = −0.09, t0 = 2.35 for females; and L∞ = 61.2 mm, K = −0.19, t0 = 2.76 for males. The gonadosomatic index (GSI) values indicated spawning to be from May to September. Absolute fecundity varied from a minimum of 143 eggs for age one to a maximum of 698 eggs for age five. Relationships between fecundity–length and fecundity–weight were described by the equations: F = 0.0002 TL3.3222 and F = 36.032 W1.0053, respectively. The equation of the relation between absolute fecundity and age was F = 25.372 t1.2343.