ARTICLE 78 FEED & ADDITIVE MAGAZINE July 2024 “Due to the negative impact of antibiotics, there is a need to develop eco-friendly alternatives to control or prevent the bacterial infections in aquaculture. At this point, immunostimulants appear to be the most promising and useful tools for the prophylactic treatment of farmed fish and shrimp. It is safer than chemotherapeutics and their range of efficacy is wider than vaccination.” In the last few decades aquaculture has been growing rapidly for food production. World fisheries and aquaculture production has attained around 177.8 million tons (FAO, 2020). Several commercially important fish species have been intensively cultured in narrow or enclosed spaces viz., tanks or cages under high density leading to adverse effects on the cultured fish with potentially stressful environment and infectious diseases (Sakai, 1999). Antibiotics and chemotherapeutics have been utilized to control or prevent the bacterial infections in aquaculture for about 20 years (Sakai, 1999). Due to increasing trend in antibiotic-resistant bacteria, regrettably the usage of antibiotics for treatment is not sustainable and successful, negative consequence on the indigenous microflora of juveniles or adult fish (Misra, 2006), and the aggregation of antibiotic residues in tissues of fish and environment inducing animal and human health issues. Due to their negative impact on interactions, there is a need to develop eco-friendly alternatives to antibiotics that may keep fish healthy, such as probiotics, immunostimulants and applications of indigenous technological knowledge for treating diseases in fish health and disease management (Sahu et al., 2007). An immunostimulant is specified as a chemical, drug, stressor that enhances the non-specific or innate immune response by interacting with the system that is activated by cells. Immunostimulants can be specified under bacterial preparations, chemical agents, polysaccharides, nutritional factors, cytokines and animal or plant extracts. Immunostimulants are chemical components which trigger leukocytes (Lunden, 2000). TYPES OF IMMUNOSTIMULANTS USED IN FISH AND SHRIMP Synthetic chemical • Levamisole Biological substances • LPS (lipopolysaccharide) • Yeast derivatives- Glucans • Polysaccharides - Chitin and Chitosan • Nutritional factors - Vitamin C and Vitamin E NOVEL IMMUNOMODULATORS IN AQUACULTURE Pathinathan Philominal College of Fishery Science Andhra Pradesh Fisheries University
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