Nanotechnology is an emerging technology which deals with the production and application of Nanoparticles of heavy meals in various fields of day to day life such as food, cosmetics, medicine, pharmacy, energy, environment and material application. But its industrial runoff may affect the aquatic ecosystem. In the present study ultra structural and biochemical changes induced by Cadmium nanoparticle in the Muscle of fresh water fiddler crab, Scylla olivacea (HERBST, 1796) was studied. Histological results revealed the loss of muscle structure, necrosis and atrophy of the muscle. Antioxidant enzyme analysis showed decreased activity of mitochondrial enzymes which reflect the disturbances of oxidation–reduction processes taking place in this organelle. The decreased activities in GPx and CAT, along with the increased activity in SOD, suggesting that there must be an oxidative stress in response to acute intoxication of Cd and that an oxidative damage was induced by the histopathological damage at the CdNP concentrations (20 ppm/kg body weight). Imbalance in the metabolic enzymes may decline the level energy in the organ system and in response to cadmium exposure the increase in LDH activity and declined SDH, MDH activity may help to maintain a balance in the energy requirement of the organism during the exposure to sublethal concentration of cadmium nano particles. So the overall results revealed the heavy metals in nanoscale may affect the ecobalance in the aquatic system which is reflected in the decrease in the population of the aquatic animals exposed the heavy metals intoxication.
