hi this is my first post and i need an anwser plz im worried about my fish, a fantail goldfish, is continuously sitting on bottom of my tank, gulping.I have just cleaned it about half an hour ago, im worried iv been told it may be nitrate or ammonia lvls, but i tested and they sed it was perfect so i dont no wats going on and im becoming a worry wart as iv lost 2 fish in my recent past alredy, not in same circumstances mind u but plz i need help