Mercury (II) impairs nucleotide excision repair (NER) in zebrafish (Danio rerio) embryos by targeting primarily at the stage of DNA incision.

•NER of UV-damaged DNA was detected in the extracts of zebrafish embryos.•Hg (II) at μM levels could abolish NER activities in zebrafish embryos.•Hg (II) imposed a minor influence on the gene expression of NER factors.•The embryonic UV-damaged-DNA binding activities were partially inhibited by Hg (II).•Dual incision of NER was shown to be a very sensitive repair stage to Hg (II).