My fish sleeps. He actually sleeps every night in the same position, next to Sponge Bob bubble blower, in between the side and the plastic plant.
Dyson II (named after house-mates boyfriend's old fish, he used to "Hoover" the food up, our Dyson has also inherited this) is smart one, I think this proves that the three second memory is false, how else would Dyson II remember to go to bed? He obviously knows that the next day will be a busy one and he needs his 8 hours beauty sleep.
Yup he's a clever fish, Mark gets up and feeds him before he goes to work, then an hour later I get up, go downstairs and feed the fish, cheeky boy doesn't tell me he's already eaten an hour before, and gobbles up as if he never been fed!
What a smart yet cheeky fish. Either way he's the longest surviving fish I've had and love him for that, I won't disturb him when he does sleep, he doesn't disturb me so all is right in the world.