The brother of city Comptroller Scott Stringer was busted for allegedly punching a patron at an Upper East Side sushi restaurant last week, according to police and sources.

The brawl broke out at Sushi Gama around 8:45 p.m. Friday, with David Stringer, 57, allegedly slugging the 33-year-old victim in the face, police and sources said.

The younger man had gotten into it with David over his “treatment of the staff and bartenders” at the Second Avenue eatery near East 73rd Street, police said.

The victim suffered a cut on his nose.

Sources said David was charged with misdemeanor assault and given a desk appearance ticket. He has to appear in Manhattan court on Dec. 16.

David could not be immediately reached for comment.

A spokeswoman for the comptroller declined to comment.