This book is a study of the serious disease causing organism Listeria and it's occurrence in fishes from Goa region-India.Fish constitutes main diet for Goan's as well as the marine food source world wide.Keeping in view of the public health, efforts were made to study the occurrence of the pathogens, Listeria monocytogenes and Aeromonas from the fishes collected from four different fish markets of Goa.Listeria monocytogenes were detected for hly A gene which codes for the pathogenicity of the organism. Results and details of the study are presented in this book.