I'm 15 and I currently own 2 oscars and one of them is looking really . My dad thinks it's whitespot but i would have thought both of them would have it if theye are in the same tank. Chong (the sick fish) has a white patch on his left side that looks like his scales are falling off and it bulges a little, it's a bit on his right side too, but not as much. Both of his fins are distroyed, he's always had lovely fins, but they went from just bone like bits to almost non existent since he's looked sick.
We've added multicure to his tank a few times but it is't improving him and i'm starting to worry, can some one please help!

the white bits are also apearing around his gills and his colour as faded

Well, i'm relatively new to the Os and never experienced any disease yet, but i think the best way to fight a disease is to perform water changes. I think your Os have got Finrot disease. U can also use medication found in the fish stores.
How big is your Tank?
GoodLuck

It is not white spot. White spot is lots of tiny pin prick sized white spots

I have never had the problem you have but i agree with jeffrey and it sounds like some sort of skin disease like fungus. I would treat with an finrot treatment or any anti-bacterial will do. However it might be caused by fighting, do your fish fight or does one hide away a lot

A pic would help us to diagnose better

What size is your tank. Can you test your water for ammonia, nitrite and nitrate. Can you post the actual readings as this will help with a diagnoses

Fish heal better when the water quality is good/better. So i would do a 30% daily water change. When you start the treatment do the water change before adding the medications. Dont forget to take any carbon out of the filter as this will remove the meds