Twenty passengers on a Brooklyn subway train were hit with pepper spray Saturday night when a man pressed the button on his can and aimed it at a man he was fighting with.

The straphangers — including children — were coughing and choking when the No. 2 train pulled into the Beverly Road station.

EMTs treated six at the scene and took the others to local hospitals. Some were given oxygen masks.

Officials said all suffered minor injuries. The sprayer was being sought.

“All of this was over a stupid fight,’’ a passenger said.