Antibiotic Therapy

But in recent times aquaculture industry has been more dependent on the use of antibiotics to prevent the infection in fishes. “Antibiotics is a substance produced by microorganisms that inhibit the growth of other microorganisms” (P.Chakraborty

Although these are successfull in eliminating pathogenic organisms to some extent they cause detrimental effect on human beings, also help in the transfer of antibiotic resistance to other strains (Gudding et.al, 1999). Antibiotic therapy can affect both the target pathogen and the normal flora. The extent of impact depends on the spectrum of antibiotic, mode of action and resistance of community (Cecilia et.al, 2010). Different antimicrobial agents influence the normal gut microbiota in different ways.

As an alternative to antibiotic therapy, probitotics has been gaining popularity in aquaculture farms. Microbiome balance is key factor to maintain overall health in fish (Gomez and Balcazar,2008). Various process like nutrient digestion, synthesis, absorption, pathogen resistance, growth, sexual maturation, morphogenesis, survivorship in stocked fish, etc can be achieved by microbiome manipulation (Martin et.al, 2014). Although there has been several definitions for probiotics, currently everyone uses the definition propsed by World Health Organization as “Probiotics are live microorganisms that, when administrated in adequate amounts, confer a health benefit on the host” (Reid et al., 2003). Several criteria are to be followed to choose a microorganism as a probiont. 1. it should be non-pathogenic. 2. The organisms should be a part of normal flora where it is applied.3. The organism should survive and grow on the site of application.4. Organism should provide beneficial effect to host. 5. Should be viable during product manufacture and storage.(GeirHovik Hansen, 2000). For commercialization, taxonomic identification of the species, in vivo and in vitro functional studies and safety should be taken care of. (FAO

are among a few microbes which are currently used in the aquaculture industry. These treatments are primarily aimed at enhance the innate immune system. A few probiotic supplements like Macrogard and Ergosan has been developed commercially for aquaculture use (Bagni et al. 2005). For a bacteria to be used as a probiotic involves the screening of fish under study and the surrounding environment. Then the bacteria is tested for its antimicrobial activity against pathogens the effect on larvae and host fish is examined (Kesarcodi-Watson et al. 2008). Most of the preparation of antibiotic is targeted at early developmental stages as they are more susceptible to pathogenic organism. Organisms like Rotifers are used as live food in aqualture. Several studies has also used such vectors to introduce probiotic bacteria into the species under study. Verschuere et al. (1999) have manipulated the microbial community in Artemia sp. for improving nutritional value and also to prevent the establishment of pathogenic and opportunistic organisms. Study by Sharifuzzaman and Austin (2009) on rainbow trout has shown that cellular and humoral immune response enhanced after treating with KocuriaSM1 probiotic bacteria. According to Wang et al (2005) when Penaeusvannamei was provided with mixed cultures of probiotics it