eDNA metabarcoding as a promising conservation tool for monitoring fish diversity in a coastal wetland of the Pearl River Estuary compared to bottom trawling.

•eDNA metabarcoding conquers limitations of traditional methods in fish diversity.•78 fish taxa were identified by eDNA metabarcoding and bottom trawling.•eDNA metabarcoding detected significantly more fish species per site and per season.•eDNA metabarcoding reflected the seasonal fluctuation of fish diversity as well.•eDNA metabarcoding could be applied to studying fish diversity in coastal wetland.