Koehler took a no-hitter into the seventh inning and tied a career high with 10 strikeouts as the Triple-A New Orleans Zephyrs cruised past the Memphis Redbirds, 7-0.
After issuing a leadoff walk in the bottom of the first, Koehler (7-5) retired 11 batters in a row. He eased into the seventh and recorded back-to-back strikeouts to keep the no-hitter intact before Jamie Romak singled.
"I didn't really have a reaction," Koehler said of the hit. "The most important thing was to win the game. I was kind of, 'Just get after the next hitter,' and that was really it."
The 25-year-old right-hander did just that, retiring Pete Kozma on a comebacker. He exited after 7 2/3 innings and 99 pitches.
"I just got ahead and mixed pitches," said Koehler, who also fanned 10 on April 30 against Round Rock. "My curveball was working well, I was able to put them away with that. [Catcher] Clint Sammons called a great game. We had a great game plan and followed that."
Selected by the Marlins in the 18th round of the 2008 Draft, Koehler has found his groove since losing his first three decisions of the season. Over his last nine starts, he's 6-2 with a 2.08 ERA and 53 strikeouts.
"When you try to pitch too fine, you fall behind. And when you fall behind, these guys can swing the bats and they can punish you," he said. "I've been getting ahead and not trying to do too much."
Overall, the New York native ranks third in the Pacific Coast League with 80 strikeouts and is tied for fourth with seven wins.
Gary Glover took over for Koehler and retired the final four batters to complete the one-hitter.
Matt Dominguez, the Marlins' No. 2 prospect, slugged a three-run homer off the bench and Sammons was 2-for-4 with a run scored.