Rearing density is one of the important factors having strong effects on growth rate, survival rate and rearing efficiency of many fish species in general and Siberian sturgeon in particular. In this study, three densities were experimented in order to identify the most suitable density for rearing Siberian sturgeon from the stages of fry to fingerling (1,000, 2,000 and 3,000 ind./m2. The fish were reared in the raceway system, fed with a combination of live feeds and commercial feeds. Results showed that the rearing densities had strong effects on growth and survival rates of Siberian sturgeon. In which, the fish reared at the density of 1,000 ind/m2 gave higher absolute growth and weight gain compared to those of the densities of 2,000 and 3,000 ind./m2 (0.21 g/ind./day
4.04 + or - 0.09 g/ind. as opposed as 0.18 g/ind./day
3.51 + or - 0.11 g/ind. and 0.16 g/ind./day
3.26 + or - 0.14 g/ind.) (P 0.05). However, there were no significant differences about these two parameters between the densities of 2,000 and 3,000 ind./m2 (P 0.05). Similarly, the fish reared at the density of 1,000 ind./m2 gave a higher relative growth rate compared with the density of 3,000 ind/m2 (59.13 as opposed as 50.8, P 0.05) but not different from the density of 2,000 ind./m2 (P 0.05). The fish reared at the density of 1,000 ind./m2 obtained the highest survival rate (85.33 percent), followed by the density of 2,000 ind./m2 (69.33 percent) and lowest at the density of 3,000 ind./m2 (55.0 percent). From the results of this study, it can be suggested that the most appropriate density for rearing the Siberian sturgeon from the stages of fry to fingerling should be 1,000 ind./m2 in order to optimize the growth, survival rate and tank rearing squares.