Quarantining a Pleco

[BigBeardDaHuZi]

I recently bought a pleco (a starry night bristlenose pleco), brought him home and plopped him in the QT tank. All's well so far. But now what? Normally, you watch your new fish, check out their behavior, see if they are eating well, but unlike any other fish I've quarantined, I never see this one. There is no way to see if he is acting normally. Normal is, he sits in his cave. I haven't seen him venture out yet.
Do I just wait for the three weeks to be up, net him and take a good gander at him? If he looks alright, add him to the big tank?

 

[Rocksor]

I would look at the underbelly and see if it is concave (like empty). I would also just remove the cave and keep no lights on above the tank.

 

[HarleyK]

Try feeding and observing at dusk/dawn with dimmed lighting.

 

[BigBeardDaHuZi]

I would look at the underbelly and see if it is concave (like empty). I would also just remove the cave and keep no lights on above the tank.

Won't that stress the fish out?

 

[DrownedFishonFire]

Won't that stress the fish out?

yes it will indeed but since its solo QT i would say keep a cave/shelter preferably the one with multiple openings to make observations more easier.