This article presents a case study on epizootic ulcerative syndrome (EUS) caused by Aphanomyces invadans in eastern mosquitofish in South Carolina. The study documents the discovery of A. invadans in a small stream and provides information on fish collections, diagnostic studies, and follow-up surveys. The identification of A. invadans was based on clinical signs and DNA sequencing. The outbreak of A. invadans seemed to be limited to the eastern mosquitofish in a specific area, and the study highlights the need for further research to understand the underlying causes of these outbreaks in wild fish populations. [Extracted from the article]