*3.4.1 Bacteriophage therapy*

Bacteriophage therapy acts as a prophylactic alternative instead of antibiotics usage in shrimp industry. These are viruses that kill only specific disease causing pathogens and acts as therapeutic agents in pathogenic infections. Unlike antibiotics, bacteriophage therapy has no residual issues and has advantages of being specific to their host bacteria, without harming other micro-organisms [10]. In aquaculture hatcheries, bacterial diseases often cause considerable economic loss across globe for hatchery operators. Bacteriophages and their lytic enzymes are in use for therapy of bacterial infections in human and animals, as biocontrol agents for food protection also as tools in molecular biology, the penentration of phage DNA inside a bacteria is promoted by lysossome produced by the phage. In yellow tail fish, a pathogen named *Lactococcus garveyi* is inhibited by bacteriophage therapy in the early 1990s (**Figure 3**) [11].
