Epizootic ulcerative syndrome (EUS) is a severe fish disease caused by the oomycete Aphanomyces invadans, affecting both wild and cultured fish in freshwater and estuarine systems. The infection causes skin ulcers, deep muscle necrosis, and granulomatous lesions, leading to significant economic losses, particularly in the Asia-Pacific region. Outbreaks are influenced by seasonal and environmental factors, including low water temperatures, poor water quality, flooding, low dissolved oxygen, and stress. The pathogen's deep tissue invasion reduces the effectiveness of conventional treatments, and its persistence in sediments makes eradication from natural water bodies difficult. Effective management requires integrated strategies, combining strict biosecurity, environmental monitoring, quarantine of new stock, and enhancement of fish immunity through proper nutrition and stress reduction. Innovative monitoring technologies, including AI-based image analysis and real-time tracking of water quality, enhance the timely detection of EUS and support more effective outbreak management.