Abstract: The study attempts to investigate the contribution of selecting optimal environmental factors as optimal temperature, light and pH condition obtained from previous experiments for growth and biochemical changes in S. platensis and S. fusiformis. Zarouk medium was used for the experiment in distilled water. For S. platensis, temperature was adjusted to 32°C, light to 2500 lux and pH 9 while for S. fusiformis, temperature was adjusted to 37°C, light to 2500 lux and pH 10. The specific growth rate and biomass of both S. platensis and S. fusiformis achieved in the present study are significantly higher than those achieved in previous cultures (p<0.05). Protein content of S. platensis was 58.6%. This value is vaguely lower than that achieved in previous experiments and the difference is not statistically significant. Protein content of S. fusiformis was 61.8%. This value is significantly higher (p<0.05) than that attained in temperature effect culture but statistically same to pH and light effect culture (p>0.05). These results suggested that favorable environmental conditions during Spirulina culture could be instrumental for good biomass production and protein production as well.