author(s)
Pabitra Barik, Raju Ram, Chandan Haldar and HK Vardia

abstract
In intensive aquaculture system, ammonia nitrogen is a key limiting factor. Removal of unionized ammonia (NH3) and nitrite (NO2) through biological activity is thus an important tool for changing such ecosystem. Nitrifying bacterial inoculants are the biologically active materials which may be used in intensive aquaculture for bioremediation. In all, 12 treatments were used with two replications factorial Completed Randomized Design (CRD) to assess the effects on different physio-chemical conditions of water. Decrease of ammonia nitrogen concentration from 10 mg L^-1 to below the minimum limit (0.3 mg L^-1) was obtained within 3 days after inoculation of microbial inoculums with aeration in water. Rate of nitrification was very slow in tanks without aeration. Soil at the bottom was not found to affect the nitrification process. Aeration and microbial application played an important role in increasing the nitrification. After acclimation phase nitrification rate was found to be increased. Therefore, it may be concluded that application of bioremediators (nitrifiers) decreased ammonia and nitrite nitrogen.