In this study, some biological characteristics of Belizem or Kura barbel ( Barbus lacerta Heckle, 1843) in Bibi Seydan River of Semirom were investigated by a monthly collection from August 2010 to July 2011. For this purpose, 445 speciments (143: females, 218: males and 84: immature) were caught by electroshocker, sein net and cast net. The collected samples were traorted to the laboratory on ice and subjected to dissection and biometric measurments. For histological studies of the gonadal tissue samples,they were fixed in 10% formalin solution using standard histological techniques, and hydrated and embedded in paraffin, then sectioned transversely at 5-6 ?m thickness. The tissue were prepared and stained with Hematoxylin-Eosin and studied by a light microscope. The Length and weight range of female fish were 6.4 to 23.3 cm and 2.65 to 123.17 g and in male fish 5.7 to 18.4 cm and 2.02 to 58.8 g, respectively. Age groups males and females were 0 + to 4 + and 0 + to 7 + , respectively. The Length-weight relationship was as W = 0.0271 L 2.7566 (in males), W = 0.0203 L 2.8909 (in females) and W = 0.0303 L 2.7354 (in all fish). Regression coefficient (b) in males, females and all fish was less than 3 and based on Pauli test, they were significantly different from b =3 (P 0.05), indicating a of negative Allometric growth pattern for this fish. The sex ratio of the speciments was 1.52 : 1 (male: female), chi-square test showed a significant difference between the sexes (p 0.01). The mean of condition factor (CF) was significantly different in both sexes and all fish during different months (P 0.05), but not significant between the sexes (P 0.05). The mean of relative length of gut (RLG) in all samples was 0.967±0.007 indicating this species is carnivorous. The Gastrosomatic Index (GSI) values in females during the year was not significantly different (P 0.05), but in males, and whole fish was significantly different (P 0.05). The average vacuity index (VI) was 24.269 in whole fish; In fact, indicated that Belizem is a relatively gluttonous group. Comparing the values of this index during the months of the year showed a significant difference (P 0.05). The highest value of Gonadosomatic (GSR) in both sexes was observed in April. Values of GSR and Hpatosomatic Index (HSI) during different months showed a significant difference in both sexes (P 0.05) but the fluctuations in GSR and HSI values were not congruent. The average fecundity was 8097±670 in 24 speciments but there was not significant correlation between fecundity and length and weight (r 2 0.5). The mean egg diameter was 0.466±0.006 mm; the minimum and maximum egg diameter was 0.03 and 2.25 mm. According to the results of histological studies, 7 sexual maturity stage inculuding: immature, in maturation, developing, advanced, ripe (ready for spawning), while the spawning and spawning were observed. In general and according to the results of GSR, egg diameter and histological studies, spawning period of Belizem occur from April to August with a peak in April. Key words : Sexual Maturity , Allometric growth, Gonadosomatic Index, Hepatosomatic Index