Brachionus calyciflorus is a freshwater rotifer that is used as a live food for intensive production of freshwater fish larvae. In this research, the possibility of isolating, purifying and semi-intensive production of freshwater rotifer was investigated in laboratory condition. Sampling was done at Anzali Lagoon in autumn 2005 and the species was identified and isolated using invert microscope. For culture of the rotifer, EPA medium was used together with freshwater chlorella sp. at 1×10^6 cells/ml density. Rotifers were produced as batch culture. Primary density of rotifers in 11 balloons was considered to be 30ind/ml. Results showed that the maximum density of rotifer reached 453°43ind/ml in the seventh day and mean growth rate per day was 0.50. The average of the lorica length and width was 204 and 167 microns and the average of the egg length and width was 121 and 95 microns, respectively. This experiment indicated that freshwater rotifer attains suitable growth parameters in laboratory condition in a relatively short time. Also, we successfully determined the protocol for semi-intensive artificial production of the species