author(s)
Parvaiz Ahmad Ganie, D Baruah, K Kunal, R Posti, Garima and D Sarma

abstract
Plankton and fish constitute a major component of freshwater environment as they play pivotal role in maintaining the biodiversity and ecosystem functions. The present study was carried out in three snow-fed tributaries viz, River Dirang chu (27.3537 N, 92.2506 E), River Sangti (27.3517 N, 92.2681 E) and River Tenga (27.2186 N, 92.43 E) of Kameng drainage, Arunachal Pradesh in the Eastern Himalayas. The key physicochemical parameters viz., temperature, pH, dissolved oxygen, alkalinity, hardness etc, recorded in tributaries range between 11.42±0.04 to 14.25±0.06^OC; 7.32±0.02 to 7.9 ± 0.03; 8.06 ± 0.05 to 8.31 ± 0.05 ppm, 33 ± 2.31 to 17.33 ± 2.31 mg/l; 26.66±1.15 to 15.33±1.15 mg/l respectively. A total of 32 phytoplankton genera belonging to 10 classes, 23 orders and 29 families were identified from the Dirang chu, Sangti and Tenga tributaries of Kameng drainage. The abundant genera identified from river sangti were Stigeoclonium (50%), Pinnularia (20%), Navicula (15%) whereas Stigeoclonium (30%), Fragilaria (30%) and Lyngbya (10%) dominated at river Sangti and in river Tenga the abundant ones were Pinnularia (30%), Acanthidium (20%) and Synedra (9%).The dominant classes identified from the drainage were Bacillariophyceae, Chlorophyceae, Cyanophyceae and Fragilariophyceae. The abundance of diverse plankton groups along with a favorable range of most of the essential hydrological characteristics indicated a good health of the water body and an environment conducive for thriving of phytoplankton.