This review discusses the use of probiotic bacteria as biological control agents in aquaculture, focusing on their potential to manipulate microbial communities and improve aquatic environments. Probiotics are defined as live microbial feed supplements that beneficially affect the host by improving intestinal balance. The review highlights the challenges and opportunities in using probiotics, particularly in controlling diseases and enhancing the health and productivity of aquatic species. Recent findings suggest that probiotics can be effective in preventing and treating diseases in fish, crustaceans, and mollusks. For example, lactic acid bacteria (Lactobacillus, Carnobacterium) and Vibrio species have shown promise in controlling pathogens such as *Vibrio alginolyticus* and *Vibrio anguillarum*. Probiotics can also enhance the nutritional value of feed, improve water quality, and stimulate the immune response of the host. The review explores various modes of action of probiotics, including the production of inhibitory compounds, competition for resources, and enhancement of the immune response. It emphasizes the importance of selecting and developing probiotics that can colonize and persist in the host environment, rather than just being ingested passively. The application of probiotics in aquaculture is discussed in detail for different stages of aquatic organisms, from eggs and larvae to juveniles and adults. Examples include the use of probiotics in hatcheries to control microbial communities, the role of probiotics in enhancing the survival and growth of crustacean larvae, and the potential of probiotics in improving the health of mollusk larvae. The review also addresses the economic and legislative considerations for the use of probiotics in aquaculture, highlighting the need for further research to optimize their application and ensure compliance with regulations. In conclusion, the review provides a comprehensive overview of the current state of probiotic research in aquaculture, emphasizing the potential benefits and challenges of using probiotics as biological control agents. It suggests that a combination of nutritional and disease control effects may yield the best probiotic outcomes.This review discusses the use of probiotic bacteria as biological control agents in aquaculture, focusing on their potential to manipulate microbial communities and improve aquatic environments. Probiotics are defined as live microbial feed supplements that beneficially affect the host by improving intestinal balance. The review highlights the challenges and opportunities in using probiotics, particularly in controlling diseases and enhancing the health and productivity of aquatic species. Recent findings suggest that probiotics can be effective in preventing and treating diseases in fish, crustaceans, and mollusks. For example, lactic acid bacteria (Lactobacillus, Carnobacterium) and Vibrio species have shown promise in controlling pathogens such as *Vibrio alginolyticus* and *Vibrio anguillarum*. Probiotics can also enhance the nutritional value of feed, improve water quality, and stimulate the immune response of the host. The review explores various modes of action of probiotics, including the production of inhibitory compounds, competition for resources, and enhancement of the immune response. It emphasizes the importance of selecting and developing probiotics that can colonize and persist in the host environment, rather than just being ingested passively. The application of probiotics in aquaculture is discussed in detail for different stages of aquatic organisms, from eggs and larvae to juveniles and adults. Examples include the use of probiotics in hatcheries to control microbial communities, the role of probiotics in enhancing the survival and growth of crustacean larvae, and the potential of probiotics in improving the health of mollusk larvae. The review also addresses the economic and legislative considerations for the use of probiotics in aquaculture, highlighting the need for further research to optimize their application and ensure compliance with regulations. In conclusion, the review provides a comprehensive overview of the current state of probiotic research in aquaculture, emphasizing the potential benefits and challenges of using probiotics as biological control agents. It suggests that a combination of nutritional and disease control effects may yield the best probiotic outcomes.