No abstract

No abstract

The present study was undertaken to find out the incidence of Motile Aeromonas Septicaemia (MAS) in the freshwater aquaculture system in three districts viz. Nagaon, Morigaon and Sonitpur of Assam. A total of 293 number pools were screened for bacteriological and mycotic studies. Out of 293 pools screened, 91 (31.05%) were found to be positive for Aeromonas species, 131 (44.70%) for A. invadans and 55 (18.77%) for S. parasitica. Among Aeromonas genera, A. hydrophila, A. veronii and A. sobria were detected with 51.64%, 21.97% and 18.68% respectively. The prevalence of other Aeromonas species (7.69%) was also recorded during the study. Data on the seasonal prevalence of MAS reveal that the highest prevalence (62.63%) was recorded during the winter season followed by post monsoon (20.87%) and premonsoon (12.08%). Thus, study suggests that motile aeromonads remain an important bacterial pathogen from aquaculture point of view in Assam, which requires regular and constant examination of cultured fish to resist unexpected losses.

The present study was conducted to evaluate the …effect of dietary selenium on growth performance and antioxidant enzymes activity in Cirrhinus mrigala for a period of 45 days. Four numbers of experimental diets were prepared, T c for Control (0 mg organic selenium/kg of diet), T 1 (2.5 mg organic selenium/kg of diet), T 2 (5.0 mg organic selenium/kg of diet) and T 3 (10 mg organic selenium/kg of diet). The water quality parameters (temperature, DO, pH, conductivity, hardness, ammonia, nitrate and nitrite) were found to be insignificant (p > .05) among all the treatments. Superoxidase dismutase (SOD) was found to be significantly highest in T 2 (6.10 ± 0.07) when compared with the other treatments. Similarly, catalase (CAT) activity in T 1 (13.21 ± 0.13) was significantly (p < .05) different with that of Control, T 2 and T 3 . Present study also revealed that 2.5mg organic selenium/kg supplemented diet (T 1 ) showed highest results in net weight gain (15.55 ± 1.36 g), net weight gain percentage (185.88 ± 8.98%) and SGR (2.35 ± 0.06 g) compared with other experimental diet. K E Y W O R D Santioxidant enzymes, Cirrhinus mrigala, growth performance, Selenium

Dikhow River is one of the largest tributaries of the Brahmaputra river basin originating from Yezami village near Zunheboto town of Nagaland. It debouches into the mighty river Brahmaputra river at Dikhowmukh, Sivasagar district, Asam covering a length of 255.8 km contributing 0.7% runoff. The geographical area of the Dikhow catchment is approximately 3100 km 2 , covering 85% of Nagaland, 10% of Assam and 5% of Arunachal Pradesh. The study area of the entire river stretch was divided into 6 stations whose elevation ranged from 90.83 msl to 669.9 msl (3 in Nagaland and 3 in Assam). These stations were selected to study the hydro-biological profile of the river stretch, its pollution status and fish diversity from January 2019 to February 2020. The important physico-chemical water quality parameters of the river in these stations like Dissolved Oxygen (5.2-10.1 mg/L), pH (7.0-8.2), Turbidity (3.8-143.8 NTU), Total Hardness (24.02-121.01 mg/L), Total alkalinity (33-89 mg/L), etc. were found to be ambient for the survival of aquatic fauna in some parts in some period of the year.