I think you mean clamped, ^-^ it's usually a sign of stress, illness, or cold. in your case I'd say stress from the ammonia poisoning. that should get better with time. ^-^ what time is it there? I usually leave mine on from ten AM to seven or eight PM... they sleep the same as we do usually, so he'll probably like the light ( daylight ) during the day, and he'll need it off for night ofcourse. and sleep. that being said, since you have a planted tank, you'll need to check how much light and how direct they like too or you'll kill them...
the plant guide here:
might help with that :3 they may only care for six hours or so. also watch for black algae, which may form in plants like moneywort if they receive too much light.
if you post in the habitat board you might be able to get tips on caring for your plants ^-^