I bought 2 angels from my LFS 4 weeks ago,i feed them flake food daily, with frozen brine shrimp1x weekly. They have always fed very well,3 days ago I did my weekly 30% water change, the next day both angels were very skiddish and my golden angel refused to eat. two days later it still wont eat. water parameters are o ammonia, o nitrite, I have higher ph of 8.0. also my red tailed shark now has a white patch on it's head. I bought frozen blood worms, all fish eat them eagerly, the golden angel will chase them eat it and spit it out. now the angel just sits facing into the front corner at the top of the tank