my second oscar has inflated and floats belly up at the surface he seems healthy as can be only filled wth air. idk what i can do to help. when my first oscar did it he was belly up for over a month before i put him down. i dont wanna lose another

Are the scales lifting. as you said your other fish died the same way I suspect dropsy. infectious to other fish. please look at the link below and dose your fish resemble these. if so I suggest you help it along the way sooner rather than later. I have tried treatment before for this on pond fish but have never been successful. if you feel your fish looks different please post a pic and give as much info as poss.

en.wikipedia.org/wiki/Fish_dropsy

www.thetropicaltank.co.uk/hddropsy.htm

Sorry the wilkipedia pics didnt work, please search dropsy pic on the net as I dont have any.

your O going to die.........it's to late. did it stop eating before he went belly up......years ago my oscar did the same thing it was protozoan infestations called hexamita 5 fish died before I found out what it was......I used a med called Metronidazole......I lost 2 discus, 1-12" oscar, & 2 gold severums.

i did not notice a drop in appetite in my fish i have six oscar in the tank and they are all healthy as can be except for the one

if the bloated belly never deflate, and he/she stop eating....
i suggest you give her/him separate tank. small chance of recovery.

did the bloat concentrated in the anal area?