Assessment of Fish Distribution and Community Characteristics in the Omcheon Stream

This study analyzed the fish community structure and distribution patterns in the Omcheon Stream, a tributary of the Tamjin River system, from May to November 2021. Fish surveys were conducted at a total of 24 sites along the stream, based on the weirs that were installed. A total of 11,305 individuals representing 23 species, eight families, and three orders were identified. The dominant species was Zacco temminckii (36.37%), followed by Zacco platypus (26.07%), which was the subdominant species. Two endangered species, <i>Acheilognathus somjinensis</i> (class I) and <i>Coreoperca kawamebari</i> (class II), were recorded, and the invasive alien species <i>Micropterus salmoides</i> was found in the lower reach of the stream (S1-S6). Ten Korean endemic species were also identified. The overall diversity index was 1.93, richness index was 2.36, evenness index was 0.62, and dominance index was 0.62, indicating a fish community structure with a distinct dominance of certain species. Species diversity and richness increased downstream, while evenness and dominance remained largely stable, except at sites S4 and S6, where the abundance of <i>Zacco temminckii</i> and <i>Zacco platypus</i> was particularly high. These results provide a quantitative baseline for understanding the ecological characteristics of fish communities in the Omcheon Stream and are expected to contribute to the effective management and conservation of regional freshwater ecosystems.