Why is my fantail goldfish so fat?

It is about almost an inch long and its head is normal size but its body is big, it looks like a ball. Its been like this ever since we bought it. Also recently the fish has been floating on the top but before when we bought it was "lazy" it really didn't swim until it went by the filter then it would swim away from the bubbles. Whats wrong with it?


i have a fantail goldfish too, everybody asks why shes so fat. it's just their breed they are bred fat. Females have a even bigger abdomen! I had her in quite a small fish tank. I moved her into a 7 gallon recentley with a filter! I have never seen her happier! Yeah she dosent go near the bubbles either. But shes still happy! And i got her some friends now shes even happier! Good luck with your fantail. They are fat by nature!