Research activities in application in application of nanoparticle on fish is increasing significantly. Areas for commercial development are the inclusion of nanoscale ingredients and use of nanotechnology in fish feeds, food packaging, the use of nano materials in the construction of aquaculture systems and application in fish health. Histology and histopathological alterations are effective biomarkers reflecting impact of environmental stressors, revealing prior alterations in physiological and/or biochemical function, culminating in impaired health (Handy et al., 2008). Biogenic gold nanoparticle have been used in the present study to evaluate the impact of its oral supplementation in Oreochromis mossambicus. These gold nanoparticle were prepared using 0.3 M HAucl43H20 (Sigma-Aldrich) and aqueous extract of Ocimum sanctum and Curcuma longa. Synthesis of biogenic and synthetic gold nanoparticle was confirmed from the UV-Vis study of surface plasmon resonance property of the colloidal solution. Juveniles of Oreochromis mossambicus in the range 7 ± 0.35 cm and 5 ±0.62 gm were stocked at 20 fish/1000L tanks and maintained at laboratory conditions. Experimental diet was prepared by incorporating 10ml of biogenic and synthetic gold nano solution per 100gms of basal feed. Non-treated control diets and aquous extract of Ocimum sanctum and Curcuma longa extract incorporated diets too were prepared. The experimental schedule was for six weeks and the fishes were fed at 2% of body weight twice daily. The biological effect was assessed in terms of histopathological studies at liver. The histopathological data revealed significant variations between treated and untreated groups. The details have been documented and discussed in the light of available literature.
