C. AMUTHA, P. SUBRAMANIAN, D. SUDHA, K. SAKTHIVEL, ABHIJIT MANNA 1Page ASSESSMENT OF MOLECULAR AND BEHAVIOURAL CHANGES ENCOUNTERED DUE TO POLLUTION MEDIATED ENDOCRINE DISRUPTION IN SOME CHOSEN FISHES IN THE RIVER VAIGAI, SOUTH INDIA 1 C. AMUTHA, 2 P. SUBRAMANIAN, 1 D. SUDHA, 1 K. SAKTHIVEL 1 ABHIJIT MANNA 1 Dept of Animal Behaviour & Physiology School of Biological Sciences Madurai Kamaraj University Madurai-625 021, (TN) INDIA 2 Department of Animal Science Bharathidasan University, Tiruchirappalli-620 024, (TN) INDIA The diversification of chemicals from various point and non-point sources discharged into the environment that can mimic or antagonise the action of hormones. These endocrine- disrupting chemicals (EDCs) can thus interact with physiological systems and cause alterations in development, growth and reproduction in wildlife that are exposed to them. The present study focused on the endocrine sensitivity of the fishes collected from three different contaminated regions of a non-perennial Holly river Vaigai, which flows across Madurai city. The contaminated locales are Sewage confluence area (Point source), Liquid food Effluent area (Point source), and Agricultural runoff area (non-point source). From these three regions, the inhabiting common fish as Oreochromis mossambicus was collected and examined for their hormone (Estrogen) and protein (Vitellogenin) interaction. The controversial results were obtained due to endocrine disruptive chemicals discharged from these contaminated sites when compared to normal reproductive fish physiology. Key words: Endocrine disruption, gonadosomatic index, hepatosomatic index, estrogen, testosterone, progesterone, gonadotropin, vitellogenin. INTRODUCTION Endocrine modulation is not new to science. It has been known of as part of herbal and classical medicine, in particular contraception, for centuries. It is a natural mechanism which