Fishes are the most abundant vertebrate on earth. They are one of the most ancient, diverse and unique fauna. Not only are they a great source of income generation and economic returns but also a delicious food option having good protein value. They are very sensitive to any changes in the habitat and reflect it back. Global quandaries of the world include climate change and pollution and the fishes are no less affected. The bearings of stress on fish make it an effective tool for pollution and bio-monitoring studies. How the fishes respond to stressors is critically variable and requires exhaustive experimental research at physiological and molecular level. Molecular biological research and study of stress physiology in fishes is gaining a quick momentum in light of unabated population ebullition. Fishes can thrive in diverse habitats and extreme climatic regime. Proper fish management at commercial level requires that the stress physiology of fish be fathomed and fish genetics be comprehended. These areas of research make us visualize the improvement of fish genes which will consequently improve the fish quality as food. In order to feed millions, man has to depend upon fishes as alternate source of food and therefore, fishery biologists are focusing their thrust area of research in these fields. We hope that the research articles deliberated in these ISCA 2019 proceedings will be of immense interest to the fishery biologists, molecular biologists, geneticists, aqua-culturists and last but not the least, young and dynamic researchers and fish enthusiasts.