The fishing guide's name was Ken Penrod, and his little boy, Jason, caught the afternoon's first fish, a six-pound channel cat Jason reeled in like a tired old stump, between bites of a cherry pie his father couldn't finish.

Less than half an hour earlier, Penrod had met his client at the Columbia Island Marina and had promised the man, who had never been bass fishing before, that he would be frying fillets of striper and largemouth bass in a black skillet by nightfall. "We'll find you a fish," Penrod had promised. "You just relax and let me show you how."

They had talked idly--over hot coffee, eggs and sausage--about the heat and the traffic and the 2 p.m. low tide that would be the best time to catch bass on the Potomac, as Penrod's boy stuffed quarters into the Pac-Man machine.

Both Penrod and his son look a little like Huck Finn, ruddy as overripe plums and full of adventure, but the guest looked ready for a shot of the varnish the fishing guide would offer only after the sun had had time to rise and clear the morning fog. "I got beer, too," Penrod told the guest. "Beer and pie and any kind of soda pop you can name. And I got some good ham sandwiches for when you get hungry."

Penrod was doing his client a favor, taking him out this day when he was scheduled to take out only his boy. Penrod has five sons, and whenever he has an open date, he takes one out on the river and asks him about school and girlfriends, feeds him cherry pies and chewing gum and shows him how to fish.

Penrod's father taught him how to fish when he was "knee-high to a grasshopper," living in Portage, Pa., a little coal-mining town where he grew up poor and fished and hunted to put food on the table.

Penrod, 40, worked construction for 21 years, first as a laborer, then as a foreman and a superintendent, before forming his own company, Kenneth V. Penrod Inc., and building churches and apartment complexes and government buildings. When he met Ken Wilson, who was to become his partner in Outdoor Life Unlimited, their hunting and fishing guide firm, Wilson was only months out of the hospital, where he had been treated for a fire-fighting accident.

Wilson owned the fancy bass rig with "The Bassin' Fire Fighter, RET." painted across his 150-horsepower Johnson outboard. Wilson practically lived on the Potomac, fishing for bass off Hains Point and Hog Island and Smoot Cove, this being his only livelihood after falling 35 feet from the roof of a burning building and injuring his back.

Construction gave Penrod a good living, but he wanted more than that back-busting, mind-grinding life would give him. He still does "a million dollars or two" of building work a year, "just to keep my hands in it," but after he and Wilson got together and formed their guide company, he knew there would be no looking back, no regrets.

He wants one day to have his own line of clothing, manufactured solely for the serious sportsman. He also wants to offer video cassettes and documentary films and to speak on an instructional circuit about the outdoors. "I may lose a lot the first five years," he said. "But somewhere down the line, I'm gonna make some money."

"All bass fishermen are frustrated guides, anyway," Penrod said. "The first thing people tell me is that my job is enviable. The first thing I say is, 'You're right.' But 12 hours a day, from 6 in the morning till 6 at night, can be tough on a man.

"You've got to always be congenial; you can't come out here in a bad mood. I absolutely insist all troubles be left at home. The people I take out here want to get away from their worries, not into mine."

Minutes out of the marina, Penrod met Wilson and his party fishing for bass off the stone wall near the National War College. Servicemen lined the wall, stood under pine trees, peeled leaves off ligustrum bushes and watched Penrod cast his line like a veteran pitcher loosening up for an easy inning.

The guest said, "I bet you could hit the head of a needle with that thing, Ken." But Penrod had no reply. He only nodded once, modestly, meaning he sure as hell could.

Wilson's party had already caught two three-pound bass. He showed his clients how to hold their fish by the lower lip and had Penrod take pictures from his boat with a 35 mm camera. "People love to look at themselves," Penrod said out of the party's hearing. "You take their picture and stick it in the boathouse and they'll love you forever."

Penrod took his wife, Maggie, fishing on his honeymoon--and has done so on every anniversary thereafter--only dreaming then in some dark region of his mind that making a living fishing for bass would ever be possible. He now owns a $15,000 boat equipped with $8,000 worth of fishing gear, but, "I would own all this, anyway. I don't know, maybe I kinda overdo it when it comes to getting bass."

This day, his client caught a striper and two largemouth bass fishing down the wall on the Washington Channel, between the 14th Street Bridge and the Tidal Basin. The guest used a shad-colored crank bait that broke before the day was out when he cast it against a stone bridge piling. With a spinning minnow, Jason caught two large channel cats at the spoils off Belle Haven, fishing the rubble. He also caught two bass at Penrod's "special, secret spot" near General's Row using a Double-Deep Rebel.

Penrod, who caught three fine largemouth bass, told his client, "One thing you want to know is that bass fishermen are egomaniacs. There are no sissies in the bass world." He then compared his own catch to the others on the stringer. "The other bass fishermen on the Potomac may catch bass, but they won't catch more than me."

Penrod's client had learned how to tie knots, read the tides and cast while sitting down. For only $125 more, the cost of a day with the master, Penrod would teach him all about lures.