A couple of months ago we brought two gold fishes for our aquarium as it was desperately in need of some new fishes. Here they are ... living happily or rather wondering about the thing (cam) in my hand.
The plus point is that they always have such expressions when I was about to feed them or perhaps they know exactly about their feeding time.
While searching, I found a very interesting article about gold fish memories. They say goldfish have a far better memory than the three second memory myth. Read it here.