I have a 5 year old oscar the has a boyancy problem. he cant swim down - he is fighting to stay upright and off the top of the tank. I have held him down but when I let go he pops back up to the top like a baloon. Any ideas ???

this is one of those situations where a reliable diagnosis is virtually impossible, we can only hazard a guess at what may be wrong. There is a possibility that there is a problem with the swimbladder. Unfortunately, swimbladder disorders are untreatable and the only alternative if it gets too bad is euthanasia. Could you possibly take some video footage and post it.

There is treatment for sale for swimbladders but i have no experience of using it so i dont know how good it is

Someone i know had a koi that couldnt stay upright so she created a sort of box out of rocks to hold it the right way up. It had enough room so that it wasnt squashed but tight enough to force it it upright. She left it for a day and it was then released and apparently the fish was ok after that. Its worth a try if the alternative is euthanasia (use large rocks as oscar are strong