Ok Ollie has been doing ok since last post in september, but yesterday his belly became swollen and it looks like he has a big golf ball behind his front two bottom fins is this dropsy and fatal.

Iv had this before I think they just get a bit blocked up from time to time.. stop feeding him and wait till it clears. when you start feeding him try peas or just stick to pellets for a few days.

I don't think it is dropsey because normally all the scale stick out like a pine cone when the fish has this condition.

I have seen something very similar to what you are describing on an Oscar in one of the fish stores a few years ago. I don't know whether it survived but it seemed okay at the time.

Is the fish still defecating? That could be a few reasons why this has happened, a blockage in the intestine could cause major swelling. However, this does rather sound like some kind of growth inside the fish. However, I don't think an internal growth would appear that quickly. Sometimes fish developed water in their abdominal cavity if they have problems with their organs. I don't see how it is possible to diagnose a huge lump like this without actually opening the fish up, or carrying out an x-ray on it.

Is the fish still eating and behaving normally? If it is , see if it will accept some shelled peas, this could help clear out a blockage in the intestine, but I wouldn't like to say this with great confidence.

I will consult my health book and see if there's anything else that I can come up with. Finally, have you done anything differently in the tank, you would also be wise to check the water conditions.

thxs i will keep you posted on if he recovers

my oscar gets something sour of like that i think its cause when
he eats he gets full like in humans when we get
full our stomaches inlarge same with oscars