u need to retset ur water, and if the ammonia shows that high again u need to do 2 BIG water changes back to back as mentioned before. also, i know Oscars will change color like that if stressed, or just to show different moods. my frineds tiger does the same thing, and his water is fine. good luck with getting the ammonia down. Oscars can be a bit of work, but are totally worth it!