Help please - Goldfish woes

[Boobonman]

Hello, we bought a pair of goldfish who live in a bowl for the entertainment of our 18mth old son, and very happy they seem too.

That is, until recently. The paler on of the two has quite a distended belly, and seems a tad lethargic. What concerns me in the more orange one has taken to chasing the other one (Fatty) around the bowl. He seems to just be headbutting him up the backside. Anyone seen anything like this before?

[Boobonman]

Yeah, thank you. Having read that it would appear dropsy is probably it. Depressingly, the article says that by the time the symptoms are apparent it is normally too late. Should I scoop him out now and save his buddy the trauma of his imminent death or just wait?

[Boobonman]

It is quite small.

Will have to get a larger one. Fatty staged a recovery, slimmed down and the other one stopped butting him, but now he has puffed up again and is getting rammed.