In the present world, various food producing sectors are gaining more importance to sustain the nutritional and food security of the world. Fish production sector is emerging as key sector to achieve the food security goals of the country and the world. Continuous focus on higher production targets has left the aquaculture highly susceptible to frequent disease outbreaks and consequent economic losses. It has been estimated that per annum economic loss due to aquatic animal diseases is approximately US$ 6 billion, worldwide. Though prophylactic measures such as maintenance of optimum culture conditions, probiotics and immunostimulants are regularly used in aquaculture, the application of medicated feed containing antibiotics often becomes the method of choice for the treatment of disease outbreaks. As is understood, prevention of fish diseases assumes paramount importance in terms of sustainable growth of aquaculture.