Cox holds an 11-ounce lead over California's Mike Reynolds, whose five bass tipped the scales at 13-15.
Rounding out the top five pros after day one on the Red River are Wes Thomas of Indiana with 13-7, Texas' Gene Eisenmann with 13-1 and Brent Ehrler of California with 13 pounds.
The highest-ranking Louisiana angler is West Monroe's Jim Dillard, who moved into to today's competition in 80th with 5-12.
Complete standings can be found at flwoutdoors.com.
Cox chose to fish the tournament from a 17-foot boat powered by a 75-horsepower Mercury outboard with hopes that the lighter rig would allow him to access areas other competitors could not.
"I started off in an area I found in the last day of practice," Cox said. "I got into a shallow pond, and it was loaded. I caught my first five in five flips. I was real lucky there was still enough water to get in there. It worked out great."
Cox said he began throwing a Chatterbait but switched tactics after the Chatterbait didn't produce the results he was looking for. He said he made the switch to a Dandy Baits jig, and the change paid off immediately.
"I pulled in and started off throwing the Chatterbait and said, 'Something's not right,'" Cox said. "So I switched to the jig. You could really throw anything in there.
"It's all just falling into place now. Well, today it did. Who knows what the rest of the week will hold. We'll see. I'm going to do same thing tomorrow."
Overall there were 525 bass weighing 880 pounds, 10 ounces caught by 132 pros Thursday. The catch included 73 five-bass limits.
Pros are competing for a top award of up to $125,000 plus valuable points in the hope of qualifying for the Forrest Wood Cup, the circuit's championship. This year's Cup will be held Aug. 11-14 out of Hot Springs, Ark., on Lake Ouachita. Pros will compete for a top prize of $600,000 – the sport's biggest award.
Pro anglers are also vying for the prestigious 2011 Walmart FLW Tour Angler of the Year that will be determined by the most points accumulated over the six Tour Majors, with the winner receiving $100,000 for their accomplishment.
In the co-angler division, North Carolina's Mike McDonald leads with five bass weighing 12-1. He is followed by fellow Tarheel Timothy Sisk, who weighed in 11-7.
The tournament continues through Sunday (May 22), with daily launches at Red River South Marina located at 250 Red River South Rd. in Bossier City, La., at 6:30 each morning.
Today's weigh-in will be held at the Red River South Marina beginning at 3 p.m. Saturday, and Sunday's final weigh-in will be held at the Shreveport Convention Center located at 400 Caddo St. in Shreveport beginning at 4 p.m.
Fans will be treated to the FLW Outdoors Expo at the Shreveport Convention Center on Saturday and Sunday from noon to 4 p.m. prior to the final weigh-ins. The first 300 kids 14 and under on Sunday will receive a free rod-and-reel combo. Fans also can register to win a Can-Am ATV, which will be given away following the final weigh-in. The Expo includes Ranger boat simulators, the opportunity to interact with professional anglers, enjoy interactive games, activities and giveaways provided by sponsors, and fans can learn more about the sport of fishing and other outdoor activities.
All activities are free and open to the public.