Hi there,
I've only had my juvenille oscars for about two weeks. At first they were a bit shy but they picked up. One is now fine and will come to the side when i enter the room but the other looks sick. There is no sign of any of the diseases, HITH white spot fungus etc but he is floating near the surface one fin out the water. I thought he was dead but he is still breathing although it appears slow? The otherone occasionally bumps him and he'll take a swim around the tank.
I really don't know what to do with him and need some help!
Thanks:(

welcome to the site

one very important question, did you cycle the tank before putting the fish in?

The next very important task you need to undertake is to test the water for ammonia, nitrite, nitrates and pH. You can go about this two ways, you can either take a sample of water to your fish shop, most of them will test the water for you. Or if you haven't got some already, get yourself some test kits and start testing the water.

Until we know what your water is doing, it is very difficult to advise any further. Please tell us if you cycle the tank before putting the fish in

Ok i will get some test kits tomorrow. Just found it strange that it was only affecting one fish the other one is fine. The tanks beenn set up for a while it had some guppies and platys in before so i assume that covers the cycling thing? I was wondering if it was maybe swim bladder? but am not really sure what else it could be?

Swimbladder disorders normally results in fish being unable to stay upright in the water, they may stand on their head, or just lie on the bottom of the tank.

If the fish breathing heavily, i.e. opening and closing its mouth rapidly