CINCINNATI – Because of a microfracture that was detected in his right wrist, right fielder Nick Castellanos was placed on the 10-day injured list on Friday by the Reds. The move is retroactive to Tuesday.

Castellanos, who was hit by a pitch one week ago, underwent a CT scan on Wednesday afternoon that revealed the fracture after initial X-rays were negative.

• Reds injuries and roster moves

“Yeah, in some ways, surprised. In some ways, not,” Reds manager David Bell said Friday about Wednesday’s results. “And I only say that because when you get hit with a pitch in that part of the hand, a lot of it is based on the symptoms and the tolerance, and just the healing process.

“But I did hear a potential bone bruise from one of the exams he had, and every now and then, that could be just slightly more than that. I’m very hopeful, staying positive, and every game we miss with any of our players, including Nick, is too many. But hopeful that it’ll continue to heal quickly.”

It was undetermined how long the Reds would be without Castellanos. He is second in the National League in batting average (.329) and tied for first in doubles (29) to go along with 18 home runs, 59 RBIs and a .965 OPS in 86 games this season.

On July 16 vs. the Brewers, Castellanos was hit on his wrist by 94 mph sinker from pitcher Adrian Houser. He remained in the game and scored on Eugenio Suárez’s two-run double but exited the game before the top of the fourth inning.

Castellanos didn’t play last weekend, but he was needed to play right field in the top of the 11th inning in a 15-11 loss to the Mets. He batted in the bottom of the 11th, and while not swinging at full strength, hit a fly ball to the warning track in right field and just missed hitting a home run.

Bell said that Castellanos did no baseball activity on Wednesday or Thursday.

In other roster moves, the Reds placed lefty reliever Amir Garrett on the paternity list and recalled infielder Alejo Lopez and starting pitcher Vladimir Gutierrez from Triple-A Louisville. Right-handed pitcher José De León, who had been at Louisville, was released on Friday.

Who plays right field?

With Castellanos out, Cincinnati’s options for right field are Aristides Aquino and Tyler Naquin. On days that Naquin moves from center field to play right field, Shogo Akiyama would be a likely center fielder. Aquino is a right-handed slugger while Naquin and Akiyama are lefty hitters.

“It’ll be day to day. It’ll be based on the opposing team’s pitcher,” Bell said of the plans to fill the void. “It’ll be based on a lot of things, just like we make all our decisions. But I would not go into it saying Shogo is going to play against every right-hander, and Aquino is going to play against every left-hander.”

On Friday vs. the Cardinals, Aquino started his third consecutive game as the right fielder.

“It’s tough because he’s a very important piece to this team and you never want any of your teammates to go on the injured list. It’s tough news for me to hear something like that,” Aquino said via interpreter Jorge Merlos.

After playing sparingly this season, there will be more opportunity to play and theoretically get better timing with more reps at the plate.

“Of course, it will help,” Aquino said. “Whenever you play every day, you have an opportunity to make adjustments as you go along. That’s just part of the game.”

Aquino, 27, came into Friday batting .246/.358/.632 with six home runs and nine RBIs in 30 games. Including the homers, nine of his 14 hits this season have been for extra bases.

“It just means I’ve done a very good job of preparing for the season and during my time up here as well,” Aquino said. “I’m ready to keep on going with that.”

Back to a five-man rotation

Following one turn with a six-man rotation, the Reds are going back to a starting five. The club announced that Wade Miley will start on Monday vs. the Cubs, followed by Gutierrez on Tuesday and Tyler Mahle on Wednesday.

Jeff Hoffman, who made the start two days ago and gave up five runs over four innings -- including a grand slam -- in a 7-0 loss to the Mets, is being moved to the bullpen.