Streptococcal infections are among the most destructive bacterial diseases affecting aquaculture worldwide, particularly in warm-water fish such as Nile tilapia (Oreochromis niloticus). Despite long-term dependence on antibiotics, streptococcosis continues to cause recurrent outbreaks, high mortality, and severe economic losses. The persistence of this disease is largely attributed to pathogen diversity, virulence variation, host?pathogen interaction, and the emergence of antibiotic-resistant strains. Recent advances in genomic and proteomic studies have provided critical insights into the adaptive mechanisms and virulence determinants of fish-pathogenic Streptococcus spp. This article reviews the epidemiology, pathogenesis, genomic characterization, and current challenges in the management of streptococcal infections in aquaculture systems.