Bacillus sp. for Prevention of Disease in Common Carp

The protein needs of the community can be met through aquaculture, particularly through common carp (Cyprinus carpio L.) cultivation. However, fish mortality caused by disease remains a significant challenge. While antibiotics are traditionally used to control pathogenic bacteria, long-term use causes resistance, environmental pollution, and bioaccumulation in fish. Probiotics, particularly Bacillus sp., offer a promising alternative to enhance the fish immune system and prevent disease. Bacillus sp. are gram-positive, rod-shaped bacteria capable of forming endospores with strong resistance to chemical and physical factors. These bacteria produce bacteriocins and enzymes that inhibit pathogenic bacteria and improve feed utilization. Numerous studies demonstrate that supplementing Bacillus sp. in feed at densities of 10^7–10^8 CFU/mL increases total leukocytes, improves survival rates following pathogenic challenge, and enhances overall immune response in common carp and other fish species. This review synthesizes recent research on Bacillus sp. application in aquaculture, demonstrating its effectiveness as a biocontrol agent and probiotic for disease prevention in common carp cultivation.