Could you post a picture of your entire tank? That might give people some other ideas. Don't give up! I don't blanch the cucumber. I just feed him WELL WASHED heels. Picture please!
Yes the fake rock in the middle is where he hides. The pleco is actually on top of it.I see no hiding rock in this picture. Is it the little thing in the center? Is that your pleco hunkered down in the back behind it? Large and multiple hides are important in a tank. Some people go for plants everywhere. As attractive as a minimal tank can be, especially when it is large, the more we mimic nature for our fish, the better for them. My fish spent the summer in the tank (galvanized tanks leach zinc so beware) featured in this video:and had many hides among the plant supports below the surface. Here's a video I just uploaded about feeding my pleco out in the open: