Chlorfenapyr
is widely used as an insecticide/miticide. Tralopyril,
the active metabolite of chlorfenapyr, is used as an antifouling biocide
in antifouling systems, and negatively affects aquatic environments.
However, it is unclear whether tralopyril is a metabolite of chlorfenapyr
in aquatic vertebrates, and there is little data on the bioaccumulation
and toxicity of chlorfenapyr to aquatic vertebrates. In this study,
the bioaccumulation and elimination of chlorfenapyr in zebrafish were
assessed, and tralopyril, the active metabolite of chlorfenapyr, was
determined. The effects of chronic exposure to chlorfenapyr on zebrafish
liver and brain oxidative damage, apoptosis, immune response, and
metabolome were investigated. These results showed that chlorfenapyr
has a high bioaccumulation in zebrafish, with bioaccumulation factors
of 864.6 and 1321.9 after exposure to 1.0 and 10 μg/L chlorfenapyr
for 21 days, respectively. Chlorfenapyr at these concentrations also
rapidly accumulated in zebrafish, reaching 615.5 and 10336 μg/kg
on the second and third days of exposure, respectively. Chlorfenapyr
was degraded to tralopyril in zebrafish; therefore, both chlorfenapyr
and tralopyril should be considered when evaluating the risk of chlorfenapyr
to aquatic organisms. In addition, chronic exposure caused oxidative
damage, apoptosis, and immune disorders in zebrafish liver. Chronic
exposure also altered the levels of endogenous metabolites in liver
and brain. After 9 days of depuration, some indicators of oxidative
damage, apoptosis, and immunity returned to normal levels, but the
concentration of endogenous metabolites in zebrafish liver was still
altered. Overall, these results provide useful information for evaluating
the toxicity and environmental fate of chlorfenapyr in aquatic vertebrates.