I'm sad to say that my betta fish Jimmy has passed on to Rainbow Bridge. He was my favorite betta, he was a crowntail and sapphire blue in color. I'm really not sure how he died but when I found him dead he looked really, really fat.. so I'm really not sure. I don't have any pictures unfournatly, but Jimmy will be in my heart forever.. Swim Free Little One.
Without a picture it's hard to tell but I know with certain types of goldfish their body shape and physionomy can cause problems (I assume it's like a serious form of constipation where they don't pass anything) and their shape gets distorted making them look mishapen and fat. With goldfish feeding them peas can help (you take them out of the shell/skin and cut them up small) If that's what it was you probably would have noticed the body shape gradually change so that may not be what it is, but if this helps someone else in future it's worth mentioning.
sweet!!! I was goingto buy that tank last night HAHAHA there was none left so next time lol ..Tikki says hi btw sowhat type you getting betta or wa.. remeber the tank is 1.5 gallon.. and fishy rule is 1 inch per gallon www.betta-square.piczo.com
R.I.P Jimmy im sorry for loss, i lost one of my favourite fish Baby he was a sliver scat i loved him so much and when he died some of my family laughed and said hes only a fish i went mad and told them its a life and he was my pet i think fish can make great pets