Abstract: In the current scenario of increasing and emerging drug resistance in various microbial pathogens, traditional antibiotics are becoming less effective and thus globally research has focused on developing alternative therapeutic regimens having efficient germ killing abilities. The leading alternatives include use of phages, prebiotics, probiotics, cytokines, avian egg yolk antibodies, toll like receptors, medical herbs and various other immunomodulatory/immunotherapeutic approaches. Out of these valuable therapies, the application of oral passive immunization using avian egg yolk antibodies (Immunoglobulin Y, IgY) offers promising future avenues for designing and developing novel prophylactic and treatment strategies against infectious diseases in both humans and animals, particularly countering the enteric pathogens. Hitherto studies confirm beneficial applications of IgY antibodies in animals (Calves, lamb and goat, cats and dogs), poultry and humans, however such studies in fish and aquatic animals are comparatively less. The present study presents as overview on avian egg antibodies, their salient features, advantages and limitations and then describes the potential therapeutic applications of IgY for the prevention and treatment of infectious diseases of fish and aquatic animal species, as well as speculating the future prospects of upcoming IgY technology. Taking into account the valuable prophylactic and therapeutic applications of IgY antibodies, further explorative research in this area could pave way for designing and developing effective pharmaceuticals and treatment options for various infectious diseases of fish/aquaculture animals as well as for safeguarding health of humans and their companion animals.