A Bronx straphanger was slashed during a fight with an apparent stranger who chased him onto a train late Thursday, cops said. 

The 25-year-old victim was fighting with a man at the East 138th Street–Grand Concourse station in Mott Haven around 9:30 p.m. when the suspect pursued him onto a northbound No. 5 train, police said. 

The attacker slashed the victim’s right index and middle finger with a sharp object – possibly a knife, cops said. 

The victim got off the train and was taken to Lincoln Medical Center with non-life-threatening injuries, police said. 

His attacker, meanwhile, who cops say had a heavy build and wore dark clothing, stayed on board. 

It did not appear the two men knew each other, according to cops – but sources say the victim was uncooperative with investigators. 

No arrests have been made.