The study compared methods (eDNA metabarcoding, visual, and capture surveys) to look at fish diversity in rivers. They wanted to see which method was best for finding different fish species in a region. The researchers found that eDNA metabarcoding can detect more fish species compared to visual and capture surveys. This means it can show a higher number of species in an area. The fish found by the traditional surveys were also found in the eDNA results. Both methods showed similar community patterns, but visual and capture surveys revealed more distinct differences in communities from upstream to downstream in rivers. This suggests that eDNA metabarcoding could be a good way to study fish communities, especially to understand patterns across regions for monitoring fish in rivers.