Fresno, Calif. ? Until a couple of months ago, John Albidrez enjoyed most of his success in bass fishing using a particular brand and color of plastic worms.

But the scale never lies.

During a night tournament at Lake McClure in June, Albidrez and his partner caught a 22-pound limit, including a big fish that weighed 5 pounds.

A few years ago, a 22-pound sack might have been enough to cash the winner’s check. Not anymore.

Albidrez could only watch as the first-place team brought 38 pounds back to the dock, including a 12-pound whopper. The team that finished second, meanwhile, caught 32 pounds, including an 11-pound big fish.

The difference? Swim baits.

The top two teams used them. Albidrez and his partner didn’t.

“For me, that was the last straw,” said Albidrez, who earlier this year became the first local angler to compete in the B.A.S.S. Federation National Championship.

“I finally forced myself to take everything out of my boat except for two rods with swim baits on them and go practice.”

Swim baits, the name given to hard- or soft-plastic lures designed to mimic both the look and swimming motion of a real fish, are the hottest craze to hit bass fishing since drop-shotting and other “finesse” techniques in the 1980s.

Although they’ve been around for years, swim baits have only recently gained popularity among local tournament anglers, Jeff Huth said.

“The secret is out,” said Huth, manager of Valley Rod & Gun in Clovis. “Guys all knew about them, but nobody was throwing them until they got ambushed in all the local tournaments.”

Or, as Albidrez put it, “If you don’t throw a swim bait, you can’t compete anymore. Simple as that.”

Why are swim baits so effective? It goes back to the commonly held belief that big fish prefer big baits.

Swim baits range from 5 to 12 inches in length and weigh up to 10 ounces. That’s as large as most hatchery-raised rainbow trout.

“Bigger fish don’t have the energy to chase small baits all over the place,” said Allen Borden, whose company, ABT Lures, has been designing and manufacturing swim baits since 2002.

“They’re looking for that one big meal.”

Borden made a big splash locally in March 2004 when he caught the Bass Lake record (15.17 pounds) on one of his own Gladiator swim baits.

Three years later, Borden hasn’t stopped tinkering. His Ahwanhee warehouse is packed with numerous swim bait designs, including a new soft-plastic series that will soon be hitting store shelves.

Aiming for the most realistic bait possible, Borden spent hours at local hatcheries watching how trout move in the water.

The dedication appears to have paid off. Not only does the new bait look exactly like a rainbow trout, down to the detailed markings and 3D eyes, but also behaves like one when being pulled in a test tank.

“Kind of seductive, isn’t it?” Borden said with a gleam in his eye. “I get goosebumps every time I see it in the water.”

Swim baits are becoming so realistic looking that Clovis tournament angler Ron Armstrong quipped, “I suspect in the next couple years you won’t be able to tell a swim bait from a real fish.”

“Everybody and their grandfather copied my idea,” he said.

Swim baits range in cost from $10 apiece all the way to $40. Some custom wood-carved models sell for as much as $100.