Abstract: Streptococcus agalactiae, recognized for its rapid transmission and high mortality rates, has emerged as a formidable adversary in aquaculture, causing substantial economic losses to aquafarmers. In China, serotype Ia is the predominant serotypes of S. agalactiae infecting fish, and it presents a concerning multiple drug resistance profile. The prevention and treatment strategy primarily depends on antibiotic therapy, supplemented by traditional Chinese herbal medicine. However, the extensive and frequently irrational use of antibiotics has resulted in a progressive increase in the resistance of S. agalactiae, underscoring an urgent need to identify and develop alternative, safe, and efficacious preventative and therapeutic approaches. It is imperative to curtail the spread of bacterial resistance effectively. This review delves into the recent literature concerning S. agalactiae in fish, encompassing pathogenesis, epidemiology, clinical symptoms, and existing prevention and treatment techniques. We conduct a critical analysis of the existing measures, emphasizing their deficiencies and potential for improvement. Furthermore, we project potential future research directions, aiming to provide a robust theoretical foundation and strategic guidance for the management of S. agalactiae infections in fish.