Bacterial population count
The water and sediment samples of both the treatment and control ponds were collected separately from different parts of the ponds using sterile conical flasks for the estimation of THB, green Vibrio and luminous Vibrio population at four different culture phases: (i) before stocking (pre-stocking phase; PS); (ii) stocking to day of culture (DOC) 30 (initial phase; IN); (iii) DOC 31- 70 (intermediate phase; IM); (iv) DOC 71 to harvest (pre-harvest phase; PH). Each water and soil sample was transferred to another sterile conical flask (200 mL) containing 99 mL of sterile diluents and serial dilution was performed to get 10-1, 10-2, 10-3, 10-4 and 10-5 suspension samples. For enumeration of THB and Vibrio (green and luminous), Zobell marine agar and TCBS medium were used respectively (Jaganmohan and Prasad 2010).