Nicholas K. Geranios Associated Press Feb. 12, 2006 12:00 AM

SPOKANE, Wash. - In the ancient struggle between man and fish, man has a new weapon.

Forget fancy lures, depth charges or precision casting guns. The new weapon requires vision - ultraviolet vision.

Called Fool-a-Fish, it comes in a bottle that sprays titanium dioxide on fishing lures and bait. The chemical lights up the watery depths like a disco ball, luring fish up to half a mile away.

Fool-a-Fish is the brainchild of a Spokane physician named Milan Jeckle - that's Dr. Jeckle to you - who combined his love of chemistry and the outdoors into a new business.

Fool-a-Fish is earning a growing reputation as anglers from Alaska to Florida enjoy success with the product.

"You catch three or four times more fish, and the biggest fish," Jeckle contended.

Researchers have discovered that while humans see in three colors - red, yellow-green and blue - fish and birds see a fourth color in the ultraviolet range, which shows up as a white glow, Jeckle said. This color is invisible to humans.

Working with David Cleary, chemistry professor at Spokane's Gonzaga University, Jeckle came up with the formula combining titanium dioxide, which is used in sunscreens, and several other chemicals.

The whitish liquid dries quickly, and it will stay on a lure for two hours, he said. It is non-toxic, odorless and washes off with soap and water. Underwater, it shines like a beacon to fish.

In November of 2004, Jeckle and two friends went to Moses Lake, in central Washington, to try it out.

"I put it on my bait and caught a 6-pound walleye," Jeckle said.

Later, he took it to Alaska and caught several 100-pound halibut.

Jeckle said many of the spray products used to lure fish are scent-based, because fish are known to search for food by smell.

"This is based entirely on vision," Jeckle said. "This is a new way to fish."

"It's not just blood that attracts sharks," he added.

"They can see a swimmer half a mile away."

Jeckle makes up batches of Fool-a-Fish in his kitchen. The spray is sold in some outdoor stores in the region, and it can be ordered on Jeckle's Web site. It also is getting written up in fishing magazines. Northwest Angler said the formula "makes it supereasy for fish to see lures or baits from great distances."

Instructors at Salmon University in Tacoma, a guide service and fishing school, also report success with the product. John Keizer, one of its chief instructors, said that he found treated herring bait caught three fish for every one caught on untreated herring.

Jeckle grew up in Green Bay, Wis., where he began fishing for perch as a boy. He practiced for three decades as a family physician in Spokane and went into semiretirement five years ago. That's what gave him the time to develop his products, he said.

Jeckle cautioned that Fool-a-Fish is not foolproof.

"It's not magic," Jeckle said. Some days, nothing will make fish bite, and other days, they will bite at anything, he said.

"This is for when it's in-between," he said.