CINCINNATI – The Reds placed Canadian first baseman Joey Votto back on the 15-day disabled list Tuesday with a nagging thigh injury that is expected to limit him for the rest of the season.

Catcher Brayan Pena was activated off the paternity list before a doubleheader against the Chicago Cubs. Pena will be one of the primary fill-ins at first base while Votto is gone. It’s unclear when he might be back.

“Our plan of attack will be to do everything we can to get him back to play over the course of the year,” manager Bryan Price said. “We don’t have a timetable on how long that will be, but the goal is to get him back and able to help us before the year is out.”

Votto, from Toronto, earlier missed 23 games while on the DL with a strained muscle above his left knee. It’s not expected to heal completely until the off-season.

Votto was limited when he returned from the disabled list, batting only .250 in 23 games. He hasn’t homered since May 10.

The knee began bothering him again last week. Tests on Monday found that he has aggravated the injury.

The Reds will consider trading for an experienced first baseman as a backup.

“I think we’ll see how things unfold here in the next couple of weeks,” Price said. “It’s a talking point, but right now that’s all it is.”

Nobody else on the roster has much experience at first. Outfielder Jay Bruce made his first appearance there since high school on Monday night. Third baseman Todd Frazier also has played at first base.

For now, Price plans to use those three at the position.

“I don’t want to create a black hole over there,” Price said. “I don’t think we will. I wouldn’t put someone over there if I didn’t feel they were capable of holding down the position. That being said, we don’t have a lot of players with any real history as true first basemen.”

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