Antimicrobial activity against fish pathogens, growth performance enhancement, and disease resistance against streptococcosis in Nile tilapia (Oreochromis niloticus)

At present, there are no safe and effective control measures for bacterial diseases in tilapia. Furthermore, the use of chemical drugs can easily lead to resistance of pathogenic bacteria, making the related diseases more difficult to control. Probiotics can improve water quality, enhance the host’s resistance to pathogens, and inhibit the growth/reproduction of harmful bacteria by decomposing organic matter in the water, activating the host’s humoral and cellular immunity, and secreting antagonistic substances to inhibit pathogens. Recently, screening antagonistic bacteria with secretion of antagonistic substances has become a new research hotspot for prevention and control aquatic animal bacterial diseases. The aim of this research was to develop a new and efficient biocontrol agent that could be used as feed additive to improve the growth performance and reduce the occurrence of diseases in cultivated tilapia.