How to Keep a Goldfish Healthy

We named our gerbils after Terri and June. Pozy would sort of trot through the kitchen and they'd be on the floor by the door. And then he would just spot one of the gerbils out of the corner of his eye, and go bonkers. That's the extent of the pets that we had. But you had a goldfish at university, didn't you? Do you remember that? Yeah, I actually originally had three goldfish. The other two died very, very quickly, as they often do. Can you tell me how they died? I mean... Well, one day they're just floating on the top. Because their fins go down