Cyanobacteria are photosynthetic prokaryotes that originated 3.5 billion years ago and are distributed throughout the world where moisture and light is available. A systemic survey of cyanobacteria was carried out in different freshwater bodies of Krishnagar Sadar subdivision of Nadia district, West Bengal throughout the year 2021. Krishnagar Sadar subdivision covers a vast area of 1,661.10km2.The subdivision is totally surrounded by the river Ganga locally known as Bhagirathi and gives rise to many freshwater bodies which are the main reservoirs of many types of cyanobacteria. During this survey samples were collected from different freshwater bodies mainly rivers, drains, ponds, jheel, rice fields etc. Altogether 35 heterocystous and non-heterocystous cyanobacterial forms belonging to the 21 genera were documented from these freshwater bodies of the Krishnagar Sadar subdivision. The most common and dominant cyanobacterial genera were Oscillatoria representing 8 species followed by Gloeothece, Gloeocapsa, Chroococcus, Phormidium, Anabaena, Cylindrospermum and Nostoc each with two species. Merismopedia, Aphanothece, Aphanocapsa, Lyngbya, Pseudanabaena, Westiellopsis, Nostochopsis, Stigonema, Tolypothrix, Calothrix, Gloeotrichia and Rivularia with one species each.


















