Juan Duran has quite the “Frankenfish” tale to tell, and it begins with a Kinky Beaver lure and a giant northern snakehead out on the Occoquan River in Virginia.

It ends — well, who knows where, as things have become murky for the man who caught the enormous snakehead on the water by Woodbridge.

Duran reeled in the fish a couple of Sundays ago where the rocks meet the mud at the edge of the Occoquan, a Potomac River tributary. He never got around to measuring his catch, except to put it on a scale, where it weighed in at a fin under 18 pounds 4 ounces.

“There had been rumors of a big one out there,” Duran said. “This was a real big one.”

Yes. In the days after landing the real-life fishzilla, Duran discovered that the world record for northern snakehead — the infamous, torpedo-shaped, air-breathing Asian predator with canine teeth and a reputation as a freakish freshwater monster — was 17 pounds 4 ounces, set eight years ago in Japan.

Juan Duran of Annandale, Va., holds the possible world-record-size Northern Snakehead he caught May 8 in the Occoquan River. (Family photo)

Duran beat the record by a pound.

There was a catch, though: The International Game Fish Association, which keeps the world records, likes to have girth and length measurements for record-breakers. By the time Duran figured that out, it was too late — he’d already given the fish to a friend, who’d turned it into supper.

Will his record catch be the one that got away on a technicality?

And what does it mean for the Potomac that such a large northern snakehead — an invasive, non-native species feared for its ecosystem-wrecking potential — was found in one of its tributaries?

Duran, 25, is a regular around the fishing holes of Northern Virginia. He was born in Arlington County, lives in Annandale and works in the parts department at Bill Page Honda in Falls Church.

Mostly, though, he wants to be on the water. He’s been fishing since he was 12 and goes out a couple-few times every week, usually on the Potomac, always to catch bass.

On May 6, Duran and his childhood friend Matt Caffi launched Caffi’s 21-foot bass boat from Occoquan Regional Park, near Route 123 in Lorton. They’d been out for several hours when Duran cast right up on the banks sometime after 5 p.m.

He was using a green-and-brown lure known as a Kinky Beaver (seriously, it’s in the product catalogue), “a big, five-inch bait that looks like a crayfish,” he said. “The bass really like it. It works really well for snakehead, too.”

He wasn’t trying to catch snakehead, but the aliens often lurk around bass, which they like to eat. He’d caught five smaller snakeheads before. Delicious fish, he said — as fried fish nuggets, in snakehead sandwiches, even in snakehead burritos. And, he said, “they look really cool. They’re like rattlesnakes with fins.”

As Duran was preparing to reel in his lure that Sunday, he felt a bump. His line darted to the right. He yanked his Shimano Clarus rod to set the hook. Fish on, game on.

“It comes up and crashes the surface, and Matt says, ‘twenty-pounder!’ ” Duran recalled. “I had a fight on my hands. It was really aggressive, thrashing around. He was going crazy.”

Eventually, Caffi got the fish into a net and plucked it out of the water. “It kept going crazy, thrashing the boat up,” Duran said. “It got slime all over Matt’s custom seats, all over me. It looked like I’d dipped my arms in a bucket of slime.”

Duran couldn’t have been happier with his big beast, even if it isn’t even close to being among the largest fish in the Potomac, where 100-pound blue catfish and even larger Atlantic sturgeon are said to swim. (That’s to say nothing of the two bull sharks pulled out of the Potomac in the same week in 2010; they both measured more than 8 feet and 300 pounds.)

The northern snakehead is a top-level predator from Asia that primarily feeds on other fish, and biologists have long feared that its presence in U.S. rivers and lakes could prove disastrous.

The first northern snakeheads in the region were discovered in 2002 in a Crofton pond, where a man who’d bought a pair to make soup decided instead to release them. Officials poisoned the pond, killing hundreds of baby snakeheads and breeding adults.

By 2004, snakeheads were being reported in the Potomac and its tributaries, alarming fishermen and scientists.

Eight years on, the species has proliferated throughout the Potomac watershed.

“But a lot of the initial hysteria was probably overstated,” said Virginia Department of Game and Inland Fisheries biologist John Odenkirk. “We’ve seen zero impact on either native or naturalized fish in the Potomac.” In a less-productive system, there might be a problem, he said. But the Potomac’s bass population, for instance, “is utterly phenomenal right now.”

The Potomac’s population of snakehead, which Gale A. Norton, former U.S. Interior secretary, once called “something from a bad horror movie,” appears to be stabilizing.

That an 18-pounder was pulled out of the Occoquan doesn’t alarm Odenkirk, who predicted several years ago that the species could thrive here and grow as large as 20 pounds or more. “I just wondered what took so long,” he said.

But Steve Chaconas, a Potomac fishing guide, said he’d never caught a snakehead weighing over 15 pounds. “I’m surprised they’re getting this big,” he said.

He’s delighted by the world record: Chaconas specializes in bass but is known to lead anglers on snakehead-fishing trips. Since news of the 18-pounder began to spread — beginning with a report on WTOP— he’s booked five snakehead trips at a cost of $375 per day (higher on weekends).

“My phone’s been ringing off the hook. All anybody wants to do now is catch snakehead.”

As for the man who reeled in the biggest of all snakeheads — Duran is trying to convince the International Game Fish Association that the record is his. He’s supplying the association with numerous photos, the scale used to weigh the fish and a 30-foot section of the 17-pound test line he used to catch it.

The group could decide to certify the record even without the measurements.

“If it doesn’t work out, I know it’s the biggest snakehead ever caught and recorded,” Duran said. “So I’ll still be proud of myself.”

And he’ll have one heck of a Frankenfish tale.