COMPARATIVE EVALUATION OF INSITU AND EXSITU FEEDING OF AEROBIC MICROBIAL FLOC IN THE NURSERY CULTURE OF TWO DIFFERENT STRAINS OF NILE TILAPIA, OREOCHROMIS NILOTICUS

S.Felix*, A.Gopalakannan and M. Menaga

This study evaluated the effect of aerobic microbial floc technology (AMF) application on immune response ,water quality and production performance of two different strains of  Oreochromis niloticus at insitu and exsitu raceways. The fish seeds of ±0.1gm at a density of 110fries/m3 in Control (without external carbon input) and AMF treatments. The GIFT tilapia and Chitralada strains of Oreochromis niloticus with an initial average body weight ± 0.1 g was cultured in nursery raceways for 30days. Distillery spentwash was added on AMF treatments as the organic carbon source at a C/N ratio of 15. Control treatments of each density tested showed more fluctuated water quality parameters throughout the experimental period. The highest TAN and nitrite-nitrogen were observed in two strains control treatment of  3.97 mg TAN/L ,4.01 mg TAN/L and 9.29 mg NO2-N/L and 9.54 mg NO2-N/L , respectively. The highest total yield  was observed in  GIFT strain of control treatment, whereas the highest survival and  NBT activity was observed in AMF treatments of which insitu treatment of GIFT strain was relatively higher than chitralada strain. Total feed used in AMF was lower than that of control treatments (P < 0.05),however there was no significant difference between insitu and exsitu systems suggesting that AMF could be continuously harvested by the fish as other source of food.