To describe the reproduction biology of the garfish, Belone euxini and differences in parameters from other populations, monthly sampling were conducted between December 2011 and July 2013 in the southeast Black Sea. Absolute fecundity ranged between 4015 and 32453 (mean: 14365 1049) and mature eggs that was left for each spawning portion (batch fecundity) ranged between 560 and 9713 (mean: 2338 243). Correlation coefficient of fecundity and total length relationships were significantly different from zero. Mean diameter of immature eggs in ovary was significantly lower than mature eggs (t-test: P = 1.54E-230). The proportion of mature eggs in the ovary ranged between 8% and 34% (mean: 16%+/- 0.7) and the number of batches was obtained between 3 and 12 (mean: 6.8 +/- 0.3) times in a year. Monthly proportion of gonad maturity stages and monthly GSI values showed that the spawning period of garfish was between May and September. The size at first sexual maturity (TL50) was estimated as 34.4 cm TL for females and 33.3 cm TL for males. The results of this study were offered as biological input parameters regarded as a reference for management of Black Sea stocks of the garfish species.