Your oto may not make it. A while back, when I noticed that one of my otos hadn't moved all day, I checked and sure enough it was dead. I had 2, and my remaining one hides all day, I hardly ever see him. Once in a while, I'll see him zipping around the tank in the early morning, but that's it.
I think I need to get him some friends. Like TankGirl said, I've recently read that they like to be in groups, which I didn't know before.
Anyway, good luck with yours, I hope he makes it.