My largest blue fish (same kind as the blue one in my pics but larger) became very sick yesterday. After reading some literature on fish sickness I determined that he must have swim bladder disease(or a swim bladder injury) He completely lost his balence and his swimming became screwed up. A soon as this happened all the other fish started attacking him. I took him out and put him in my hospital tank. The information I read said to put him in a shallow clean tank with an antibiotic. I went to petsmart to buy an antibiotic and could not find one. I did find a product called APPLUS+. It says it is Anti-bacteria, bacterial infection treatment. It says the active ingredients are formalin, benzalkonium Chloride. Is this an approriate medication for swim bladder disease? Does anyone have any advice? Also should I be feeding the fish while he is being medicated. I fed him one pellet last night and he ate it. Advice is appreciated. Thanks.