A Queens dad has become a video vigilante, setting online traps for potential child predators and then blasting the real-life confrontations on Facebook for everyone to see.

Many have questioned Tony Blas’ methods and motivations, but few can argue with his results: So far he’s netted nine men in his virtual web, including an upstate teacher who was arrested Tuesday after the State Police viewed one of Blas’ gotcha clips.

Jonathan Castell, 44, a math teacher at Middletown HS, was charged with attempting to endanger the welfare of a child, police said. School officials suspended the 20-year educator “pending further investigation,” according to the school’s Web site.

Blas, a stocky, 36-year-old plumber, and his crew of eight stay-at-home moms began hunting for sexual predators two months ago. The team posts ads on dating sites claiming to be women in their late teens and twenties.

Once they get a response, Blas explains, they drop the bait: “Really, I’m only 13, 14 or 15 years old.

“If the men keep talking to us, then we know to keep after them,” he says.

In some cases, the female decoys send old photos of themselves to keep their targets on the hook. A meeting is eventually set up somewhere in the city.

However, the target is not greeted by a pretty teen, but a beefy, bearded Blas in a black bandana — with his smartphone camera rolling.

“You came all the way from Middletown to meet a 15-year-old girl? You think that’s right?” Blas barks at Castell in the Facebook video — viewed by 342,000 people so far — of the July 27 sting in Queens.

“I wasn’t planning on doing anything. I just wanted to hang out,” says the educator, perspiring profusely. “I just wanted to meet her. I wanted to see if she was for real.”

Blas continues to shame Castell, who’s wearing a Captain America T-shirt, while following him down the block.

“You’re sweating like a f–king guilty person on trial right now,” Blas says. “People like you make me f–king sick. You came out here to take the innocence of a f–king child.”

Castell had exchanged messages with one of Blas’ helpers, who went by “Brittany L.” on the Tagged app for a week before they agreed to meet at a McDonald’s in Glendale, Queens, according to a criminal complaint.

At one point during their Web chats, Castell told Brittany “he was dreaming about me and that it involved a can of whipped cream and a cherry on my tummy,” the decoy told investigators, according to the complaint. He also called her a “tease” and said he “thinks about me all day long.”

He sent the girl several photos of himself, including one in his bed and one in his bathroom with his shirt off, the complaint says.

When asked if he would bring a condom to their rendezvous, he allegedly replied, “Yes, I can.”

The 8-minute clip, posted the night of the sting, went viral, making it into the hands of Middletown HS principal Tracey Sorrentino almost immediately.

“It was brought to her attention by some parent groups,” said Trooper Steven Nevel, a State Police spokesman. Four days later, Castell, who made $97,000 last year, was cuffed at his home.

To Blas, the arrest is proof his controversial mission and vigilante methods are justified.

“I’m shining a much-needed light on these cockroaches,” he told The Post during one of his stings last week. “It’s about exposing them and letting people know who they are.”

Blas’ motivation comes from a deep, dark place: he was sexually abused by a close female family member for years as a child.

“If somebody can do that to their own family, anybody in the world is capable of doing that to a child,” said Blas, who has two daughters ages 5 and 11.

He also seems hungry for redemption. He admits he is a former heroin addict who robbed drug dealers and did time in prison before getting clean and turning his life around.

“Finally being able to do something positive means the world to me,” said Blas.

He was also inspired by a movement in the UK, spread through social media, where vigilante groups with names like Dark Justice, Guardians of the North, Silent Justice and Stinson Hunter have sprung up in the last few years, according to reports. Canada has followed with a group called Creep Catchers.

“I thought, ‘Why is no one doing this right here in my city?’ ” Blas said.

He began by posting an ad on a dating site claiming to be a 13-year-old girl. The response, he said, was “disgusting.”

“There were way too many grown men saying ‘Yes’ to meet a child,” he said.

Blas calls his group “Team Loyalty Makes you Family” — its Facebook page has attracted over 30,000 followers.

His team conducted its first “To Catch a Predator”-style sting in a video posted June 9 at the Louis H. Pink Houses in Brooklyn, where Blas confronted a bearded, balding man looking to meet a 15-year-old girl.

Most of the “decoys” are moms, some of whom will work 16 hours at a time hunting for pervs, Blas said.

“As soon as I saw one of his videos I was hooked,” said one helper, who asked to remain anonymous for safety reasons. “I knew I needed to join. It feels so good to call these dudes out.”

This past Tuesday, she joined Blas on a sting in Queens to expose a 44-year-old Staten Island man. Posing as a 15-year-old, she and the man had been exchanging texts for five days.

“I want some sex … and a little neck to get me ready. If everything goes good, you can be my little shorty and I can pick you up some things from time to time … Like Jordans,” one of the man’s texts reads.

The 22-year-old helper, a social-justice major in college, didn’t mind putting herself at risk to help in the dragnet.

“I really want to catch this guy. He’s sick,” she said.

But Blas has plenty of critics.

Facebook shut down his page for several days last week because it “violated our community standards,” a spokeswoman said. He switched to YouTube, which also shut down his page.

Facebook reversed its decision on July 27. The site declined to explain its thinking.

One policing expert called Blas’ vigilante tactics dangerous.

“When someone gets cornered like a rat, that’s when they do stupid things to get away,” said retired NYPD Sgt. Joseph Giacalone, an adjunct professor at John Jay College of Criminal Justice. “They could come armed to the teeth knowing it could be a trap.”

The confrontations could also scare the men away from using online dating platforms — and from the undercover, online cops trying to catch them.

“This is not gonna end well if he keeps this up,” he said.