i turn mine on as soon as i get up and shut them off before work only five hours but the sunlight is there till dark but because of spawning they have not been on for 4 days and yes my plants all croaked
Yes, as far as I know, fish do sleep. Only thing is that is doesn't really look like they're sleeping, because they just hover (like they do during daytime as well). But the loose their coloration at night.
Here's some pics of redbellies that just woke up:
It's kinda when I wake them up when I come home late; they swimming around like they are completely drunk, bumping into each other, the tank and decoration
And p's crap as well: I noticed their poop is very lightly colored, compared to those brown string you see hanging from most fish (perhaps due to their diet). They also kinda "shoot" the crap, instead of leaving it dangling around...