محمد حسین خانجانی

As a result of the use of antibiotics for disease prevention, many problems arise, including their persistence in body tissues, the emergence of antimicrobial resistance, and disruptions of the digestive system's microbial flora, which ultimately threatens aquatic animal health. Instead of thinking about how to treat diseases, farmers focus on how to prevent them. Probiotics are live microbes used as additives to water and food to improve the health of cultured aquatic animals. When selecting microbes as probiotics, three characteristics should be considered: 1) exhibit antagonistic properties against pathogenic bacteria. 2) have colony-forming properties, and 3) Potentially increase the host's resistance to the pathogen. The bacteria must also compete with pathogenic bacteria for food, be able to attach to the intestinal wall and stimulate the immune system. According to studies, probiotics produce inhibitory substances that prevent pathogenic bacteria from growing. The antibacterial effect of probiotics can be attributed to the stimulation of the immune system, the production of antibiotics, bacteriocins, enzymes, siderophores, hydrogen peroxide, and changes in pH due to the production of organic acids in the intestinal environment.