Aquaculture is a fast-growing sector with a high scope for augmentation. Microalgae are frequently used for fish larvae culture. Hatcheries face many problems regarding the maintenance of a stock culture of the microalgae. Long term maintenance of microalgal species by serial sub culturing is often expensive, time-consuming and leads to genetic change. The present study is aimed to develop an alternative method for the long-term preservation of stock cultures. In this research, the cryopreservation protocol has been used for the preservation of Nannochloropsis sp at – 20° C using two criteria as different concentration of internal (Me2SO, MeOH, glycerol and ethylene glycol), external cryoprotectants (sucrose and sorbitol) and equilibration time (30 and 60 minutes). The results showed that the preservation of Nannochloropsis sp is feasible using this methodology. The present study proved that 10 % of Me2SO had the maximum viability at 30 minutes equilibration time and that the same concentration of cryoprotectant had resulted in the maximum viability after 6 months of preservation. From the study, it is evident that the microalgae can be preserved for a long time without using liquid nitrogen.

水产养殖是一个快速发展的部门，具有很大的扩大范围。微藻常用于鱼类幼虫养殖。孵化场在维持微藻的种群培养方面面临许多问题。通过连续的继代培养来长期维持微藻物种通常是昂贵，费时的并且会导致遗传改变。本研究旨在开发一种替代方法，用于长期保存种群培养物。在这项研究中，低温保存规程已用于在– 20°C下使用两种标准作为内部浓度（Me2SO，MeOH，甘油和乙二醇），外部低温保护剂（蔗糖和山梨糖醇）和平衡时间来保存Nannochloropsis sp。 （30和60分钟）。结果表明，Nannochloropsis sp使用此方法是可行的。本研究证明了10％的Me2SO在30分钟的平衡时间具有最大的生存能力，并且相同浓度的冷冻保护剂在保存6个月后具有最大的生存能力。从研究中可以明显看出，无需使用液氮即可将微藻保存很长时间。