If anyone knows what could be wrong with my tiger oscar. She's 71/2 years old. She has these yellowish round tumors in her mouth and it is blocking any food to get in her mouth. I have had the water tested 3 times now and everytime everthing is OK. I've treated the tank with antibiotics Erythomyocin - didn't work. I've just completed a 7 day Melafix treatment - didn't work. The tank has had 3-5o% WATER changes and all ornaments and gravel has been removed. Other fish don;t seem to be effected - since treatments began I can not get the water clear - it was clear before I started these treatments. I feelso bad that I cant' help her, she just seems to be deteriorating and has not ate at all this week, usually she attempts to try and get food down. PLEASE ANYONE HELP US!