Mismatched middle school buddies — boys 11 and 13 — from different boroughs went missing Friday, police said, and believe that they ran away from home together.

Six-foot, 215-pound Warren Garrett, 13, of the Bronx and his Democracy Prep Harlem Middle School classmate Alfa Barrie, 11, who stands at 5-foot 2-inches and 100 pounds, from Manhattan, were last seen together in the Anas Fish Market at E. 145th St. and Lenox Ave. in Harlem around 6 p.m.

A worker there said that Warren bought fried fish and French fries and then left.

“There are millions of eyes and ears in our city and we’re asking all of them right now to help us find these children,” NYPD Manhattan Borough North Chief Ruel Stephenson said at a press conference in the Bronx on Tuesday afternoon. “Investigators believe because they are friends, they could be together.”

Alfa’s family reported him missing Sunday morning and police put out a photo of the boy, sporting a white hat, matching floral bowtie and vest and pink pants.

“Because of their age, we’re very concerned,” Deputy Chief Brian Gill said. “We’re going to search land, air and sea.”

Warren’s parents told police their son was missing Monday afternoon around 3 p.m.

Cops put out a photo of the strapping 13-year-old wearing a tan knit cap and a black T-shirt with a teddy bear on it that said “Heart Breaker.”

Fatima Diallo, 22, Alfa’s sister, said that she last spoke to the 11-year-old on Friday before she went to work. She said that her brother and Warren, who goes by the nickname “Men Men” are best friends.

“They are very close,” she said.

When her brother didn’t check in, as usual, alarm bells went up with the family.

“He didn’t give us a call like he usually does,” she said. “So we knew something was up.”

Alfa has never run away from home, the boy’s uncle, Ahmadou Diallo, 60, said. His mother is grief-stricken over the disappearance.

“His mother hasn’t slept in days. She doesn’t eat,” he said. “She just waits and cries.”

The frantic family hopes that the resources of the NYPD and the public’s help will bring the boys home.

“We’re hoping for the best,” Diallo said. “With all the help from the authorities and the media, we feel that we are not alone”