Immunostimulant Effect of Seaweeds in Channa punctatus Challenged by Aeromonas hydrophila

The current study focused on to evaluate the bioactive potential and immunostimulant effect of seaweeds in striped murrel Channa punctatus against the fish pathogen Aeromonas hydrophila. The aqueous extracts of seaweeds, Glacilaria foliifera, Acanthophora spicifera and Ulva lactuca were obtained in four different concentrations (25 µL, 50 µL, 75 µL and 100 µL) and evaluated for their immunostimulant potential.  Aqueous extract of G. foliifera and A. spicifera has shown promising activity against fish pathogen. G. foliifera exhibited higher bacterial inhibitory zone of 8mm at 100 µL concentration followed by A. spicifera with 6mm at same concentration. The disease challenge study was used to ascertain the immunostimulant efficacy of active seaweed extracts. C. punctatus was administrated with the A. hydrophila and then fed with artificial feed incorporated with seaweeds extract.  The survival rate seems to be higher in G. foliifera (80%) when compared with A. spicifera (60%). Observed result shows that both seaweeds possess active metabolites which may pave the way for the discovery of novel compounds with immunostimulant potential, which can be used in the field of aqua industry to augment disease management. Keywords: Seaweed, Bioactive compounds, Aeromonas hydrophila, Gracilaria polifera