Enumeration and isolation of aerobic bacteria specially from the fresh water Grass carp (Ctenopharyngodon idella) were done. The average total viable numbers of bacteria in slime/skin, gills, intestine of fishes, fish diet, aquatic plant, aquatic insect and pond water were found 6.7x10³-1.2x10⁵,  4.2x10⁴-1.6x10⁵, 1.6x10⁴-1.7x105,  3.8xl02-5.4x10³, 1.8xl02 4.1x10³,1.2x102-4.4x10³ and 5.2xl 02-4.4x10⁴ CFU/ml respectively. Gram positive bacteria were the dominant microflora in all samples. The predominant aerobic bacterial flora isolated from these samples were Pseudomonas, Aeromonas, Staphylococcus, Micrococcus, Enterobacteriaceae (different members), Bacillus, Streptococcus, Vibrio and Salmonella. The enzymatic activities of fish isolates were also studied and were found 87% lipase producer, 57%protease producer and 29% amylase producer. The maximum amylase and pro tease activities were shown by Bacillus licheniformis and Bacillus cereus and the maximum lipase activity was shown by Aeromonas hydrophila on solid basal medium.

Enumeration and isolation of aerobic bacteria specially from the fresh water Grass carp (Ctenopharyngodon idella) were done. The average total viable numbers of bacteria in slime/skin, gills, intestine of fishes, fish diet, aquatic plant, aquatic insect and pond water were found 6.7x10³-1.2x10⁵,  4.2x10⁴-1.6x10⁵, 1.6x10⁴-1.7x105,  3.8xl02-5.4x10³, 1.8xl02 4.1x10³,1.2x102-4.4x10³ and 5.2xl 02-4.4x10⁴ CFU/ml respectively. Gram positive bacteria were the dominant microflora in all samples. The predominant aerobic bacterial flora isolated from these samples were Pseudomonas, Aeromonas, Staphylococcus, Micrococcus, Enterobacteriaceae (different members), Bacillus, Streptococcus, Vibrio and Salmonella. The enzymatic activities of fish isolates were also studied and were found 87% lipase producer, 57%protease producer and 29% amylase producer. The maximum amylase and pro tease activities were shown by Bacillus licheniformis and Bacillus cereus and the maximum lipase activity was shown by Aeromonas hydrophila on solid basal medium.