Ichthyofaunal Diversity and Physico-chemical Analysis of Water in the Middle Stretch of Vembanad Lake, Kerala, India

The status of finfish and shellfish diversity and monthly variation in their distribution and abundance were investigated in the middle stretch of Vembanad Lake at 4 selected sites in Kerala. The study was carried out for a period of 7 months from December 2022 to June 2023. In total 31 species of finfishes and shellfishes belongs to 8 orders, 23 families and 29 genera were recorded from the study areas. Calculated values of Biodiversity indices were Shannon Weiner diversity index highest at Vaikom (3.4022), Simpson diversity index highest at Manakunnam (0.9538), Margalef’s richness index highest at Manakunnam (4.346) and Pielou’s evenness index was highest at Thaneermukkom (0.8573). Etroplus suratensis and Villorita cyprinoides were the most abundant species from all four study sites. Three species are under the category of threatened they are Oreochromis mossambicus, Horobagrus brachysoma and Hyporhampus xanthopterus. The result of the present study indicates that the Northern part of Thaneermukkom barrage is endowed with rich edible fish fauna. The physicochemical parameters of water were analyzed during the pre-monsoon and monsoon periods. Salinity was higher on the Northern side of the barrage. During the pre-monsoon period temperature, EC, TDS, alkalinity and salinity were high and during the monsoon period hardness, DO, BOD, Phosphate and Nitrate were high when compared with pre-monsoon but all are within the recommended limit.