I have a goldfish.

I have a goldfish, but we originally had two. The bigger one (Shiner) was always bullying the other one (Tigger).
When we had had them about 1 1/2 years, Tigger developed a tumour, but kept his friendly cheerful personality! To help you picture them, the Shiner has the personality of a killer whale and Tigger was more like a dolphin (coming out of the water to be fed etc.)