What Does “green around the gills” mean?
Definition:
If you look green around the gills, you look pale or sick.
Origin
The phrase appeared in the mid-1800s but the origin is unclear.
Gills refer to the organ through which fish breathe. They are normally red not green. If a fish has green gills, it is probably sick.
A variation of this idiom is green about the gills.
Example(s)
There is something wrong with him. He looks green around the gills.
The passengers looked green around the gills after the trip!
When she got back from her date, she looked clearly green around the gills.
This idiom is in the health category.