*3.4.3 Probiotics*

Probiotics gaining more attention in recent scenario in all sectors including aquaculture, agriculture and animal husbandry when considering other remedies probiotics acts as a better option rather than incorporating antibiotics to control pathogens in aquaculture. The term probiotic has been defined as a mono or mixed culture of live microorganisms which can be applied to animal or human to enhance the immune system. The animal health is then improved by the removal or decrease in population density of pathogens and by improving water quality through more rapid degradation of waste organic matter (sludge). Environmental microbiology and biotechnology have advanced in the past decade, to the point that commercial products and technologies are available for treating large areas of water and land to enhance population densities of desired microbial species or biochemical activities. The practice of bioremediation is applied in many areas of interest, but success rate varies in different areas, depending on the environmental conditions, nature of products and the method of usage by the consumer, the probiotic that are added must be selected for specific functions. Bioaugmentation and the use of probiotics are significant tools for aquaculture but their efficiency depends on understanding the nature of competition between disease causing pathogens and desired strains of bacteria. *Bacillius* spp.*, Lactobacillius* spp.*, Pseudomonas* spp., nitrifying and denitrifying bacteria are some of the commonly used probiotic in shrimp culture.
