yea not at ease. armatus and payaras in general dont crash into their surroundings unless they freak out and dart.
he might be more comfortable hunting when lights are off, possibly the lights are too bright? could be that turning off the lights scares him (if so this may be a big issue later as they get big enough to kill themselves).
if he's crashing into the glass while hunting, Im guessing the tank is too small, these guys are pretty coordinated and aware of surroundings