I came home late tonight (around 11:45pm) and turned on the lights and went to feed Walter. It appears as if he was sleeping and I guess he didn't want to be woken up... he wouldn't eat any of his food and mostly stayed at the bottom of the tank, moving behind various objects and plants. He would only come to the surface for a breath and even then he would jet up there and then jet back down.
I turned off most of the lights and now he's acting more normally. I suppose I'll try not to disturb him from now on if he's gone to bed.
I also ran some tests on the water, as he's in a new tank and I thought it might have something to do with ammonia or what not, however the water tested low for NH, NO2, and NO3. Also the PH is at 7.2, which is a little higher than I'd like it but not high enough to concern me.
I suspect he might also be a little bored of his food, I'll go to the store tomorrow and get him a treat.
I'm just wondering if anyone else has noticed this? Does anyone else's fish get flustered if the lights come on at night?