For the last few days my Oscar have been acting really werid, its mouth is constantly opened. It seems to be breathing heavy and it has not been eating as much as it use to. I have two other oscars in the tank and they are acting normal with a healty appetite. I just did a water change yesterday and my oscar is still behaving oddly. I read that others on the forum have had similar experiences, but haven't read a consensus on what the problem might be. Is it a diease? If so what kinda treatments can I get. Thanks! 