Backgroud: The present experiment was conducted to investigate the effects of insitu jaggery based biofloc on biogrowth performance, physiological immuno response, digestive enzyme activity, nutrient composition and disease resistance of Etroplus suratensis. 
 
Method: The fingerlings of pearlspot, E. suratensis with an average body weight of 5.67&plusmn;0.08 g was stocked at the rate of 150/m3 in treatment and control system. The insitu biofloc was produced in 2.4 ton capacity outdoor tanks using jaggery as carbon source at two different C: N ratio of viz, 10: 1 (B1) and 20:1 (B2), where clear brackishwater system and without carbon source as control. 
 
Result: The levels of ammonia nitrogen, nitrite&ndash;nitrogen and nitrate&ndash;nitrogen were reduced in the insitu biofloc compared to control while TSS and TS were increased significantly in all insitu biofloc compared to control.&nbsp; The physiological immuno responses such as Respiratory burst test, Myeloperoxidase, serum lysozyme and antioxidant enzymes activity Superoxide dismutase &nbsp;and catalase were found to be significantly higher in B2 at end of the trial. Stress parameters glucose and cortisol were significantly lower in jaggery based biofloc system especially in (B2) C: N 20:1 compared to control. The fishes from the jaggery based biofloc groups possessed significantly (P&lt;0.05) higher immune status as compared to control. The digestive enzymes activity such as amylase protease and lipase, of fish was higher in biofloc treatment and lower in control. Compare to control the nutrient composition of E. suratensis was significantly higher in the treatment groups. Moreover, jaggery based insitu fishes showed the lower cumulative mortality rate and Enhanced relative levels of protectio after experimental challenge with&nbsp;A. hydrophila compared to control.

Influence of in situ Biofloc Production on Bio Growth Performance, Physiological Immune Response, Digestive Enzyme Activity, Nutrient Composition and Disease Resistance of Etroplus suratensis&nbsp;