In the present research, the removal of high concentration of ammonia, nitrite and nitrate was determined by using the efficient ammonia-oxidizing bacterial isolates (AOB AMS 1, AOB AMS 2, AOB AMS 5 and AOB AMSS 1) along with the consortium of all four bacterial isolates from the aquaculture both in lab-scale as well as in-situ at bioreactor level. It was found that the highest percentage of ammonia was degrade by AOB AMS 2 (99.64%± 5) followed by AOB AMS 5 (99.51%± 4.6), AOB AMSS 1 (99.38%± 5) and AOB AMS 1 (89.66%± 3.5) from an initial concentration of 30 mg/L whereas from an initial concentration of 60 mg/L, the removal rate of each strain was AOB AMS 5 (99.36%± 5), AOB AMSS 1 (99.15%± 5.60), AOB AMS 2 (98.78%± 5.3) and AOB AMS 1 (88.36%± 3.2) and their consortium removes (99.97%± 5.20)at 60 mg/L. Further, in-situ transformation was carried out in the river water with 5% of inoculum. Their growth was monitored (initial and final) by observing the colony forming unit (CFU) and transformation of ammonia and nitrite was also observed and it was found that (100 ± 2%)of ammonia was removed. The growth of consortium was 3 × 10