I have a pet goldfish. I've had him for about 8 or 9 years now. I'm surprised at how intelligent he, and presumably other goldfish, are. For example, I've trained him to swim up to the surface for meals by turning the fish tank light on. Whenever I turn the light on, he happily swims to the surface to be welcomed by the fish food. This is just conditioning, but I never knew it worked on goldfish, too. Furthermore, (and this relates to this article) he only gets excited whenever he sees me. I guess it's because I'm the one who gives him food. I have a sister, a mom, and a dad, but he doesn't give them as much attention as he gives to me. No matter where I walk around the tank, he tries to swim towards me. He can probably distinguish my face from others, because even after I got a haircut that made me look quite different than before, he still recognized me. He's really intelligent, and debunks the common myth that goldfish have a memory span of 3 seconds.