Can anyone tell me why one of my Oscar's changed colors over night? Last night it was fine today its like it changed clothes,The dark places have gone very,very dark.

Many animals change colour for different reasons. They can change colour when breeding, if they are agitated, stressed out etc. Has anything different changed in the tank. Have you moved anything around, added anything to the tank? You might also want to check the water conditions. Illness could also make fish change colour. Although fish often go a lot paler when they are ill

I don't get a chance to move anything, they fix it the way they want. I just got one of them about a month ago and they don't get along. They started fighting the next day, they were making bad bites, part of a tail on one, place on head, another on the side, So I put in a divider they moved all of the rocks up to the divider, when one does get through they fight again. they fought again yesterday could that be it?

I would think that the situation they are in at the moment has got something to do with the colour change. I have seen Oscars change colour quite dramatically. It will be interesting to see if your Oscar changes back again. It should do, apart from juveniles, I had not known Oscars to completely change colour and stay that way.