Azolla a dichotomously branched free floating aquatic fern is naturally available mostly on moist soils, ditches marshy ponds and is widely distributed in tropical belt of India. The fern is capable of fixing atmospheric nitrogen in the soil in form of NH4‌+ and becomes available as a soluble nitrogen for the wet land rice crop, which is the major cereal for the people of the North East. The remarkable feature of Azolla is that its symbiotic relationship with Cyanobacterium (Anabaena azollae), which remained on the dorsal leaf cavity of Azolla. The fern provides protein substances to Anabaena (BGA). The BGA then absorbed the atmospheric nitrogen and decomposes it through enzymic activity and converted into soluble ammonia.