MIAMI -- A.J. Burnett was dominant -- this time for just six innings.
"Not all of them are going to be easy, and this one definitely was not easy," said Burnett, who pitched complete games in his last two starts. "I had some issues locating the fastball tonight. Thank God I had my curveball."
Burnett yielded two earned runs for the fourth start in a row, along with four hits, five walks in 115 pitches. The 13 strikeouts were one shy of his career high.
"I know he threw a lot of pitches, but that was among the best (performances) I've seen -- ever," said Cincinnati's Adam Dunn, who extended his hitting streak to seven games with an RBI single in the first.
Reliever Matt Perisho (1-0) pitched a perfect seventh inning, and Guillermo Mota a 1-2-3 ninth for Florida's first save of the season.
"I had to wait two weeks; I feel like I've taken 200 pounds off my shoulders," Mota said. "I want to write on the ball, 'I've had to wait two weeks for this save.'"
Castillo's triple to deep center field followed a single by pinch-hitter Jeff Conine and a bunt hit by Juan Pierre. Both runners advanced when left-hander Kent Mercker (1-1) fielded Pierre's bunt, spun and threw wildly toward first for an error.
"At that point, I wish I could see where Pierre was so I could eat it," Mercker said of the error. "Then with runners on second and third, I tried to pinpoint the pitch to Castillo. It was right down the middle. Bad pitch, bad night."
Castillo, whose eight-game hitting streak was snapped Thursday, had three hits and reached base in each of his four plate appearances. Florida's Alex Gonzalez had a two-run double in the fourth.
"Gonzo came through with the big double, and Louie finished it off," Marlins manager Jack McKeon said.
After Sean Casey led off the third with a single, Marlins pitchers didn't allow a hit until Jim Mecir gave up Rich Aurilia's two-out single in the eighth.
Reds starter Aaron Harang gave up two runs, eight hits two walks and struck out six in six innings. He also had his first career RBI in the second.
Harang, who was 0-for-6 this season and 5-for-84 in his career, hit a grounder up the middle to score Aurilia from second with one out to make it 2-0.
Gonzalez lined a two-run double into the left-field corner in the fourth to tie it 2-all.
"I kept us in it, and then Alex came up with the big hit," Burnett said.
The Detroit Tigers are the only team without a save in the majors. ... With one hit in three at-bats against Burnett, Casey improved to 11-for-18 overall against the right-hander. ... Florida's Mike Lowell, who entered in a 5-for-44 slump, was dropped to seventh in the order for the first time since hitting there 17 times in 2002. ... Burnett became the first pitcher to hit at least two triples in a season since Houston's Mike Hampton had three in 1999 when he recorded one in the fourth inning. ... Burnett struck out 14 against Colorado on Aug. 29, 2004.