1st try posting a pic before you call the green sunfish in the pic bad quaility. Has your's been positively ID?
I'll take a guess that being a NA native it probably needs colder water then the tropical fish you are keeping it with. Yes it may survive but possibly with a shortened lifespan.
If your water is clean your Oscar is going to grow about 1" a month. There is more to worry about with the oscar in a 55 than just his size, oscar are dirty fish and will polute the water quickly.
I'd suggest you do some reading before aquiring anymore fish, you're already in over your head, and even though you are doing the right thing by posting and asking questions you don't seem to want to listen to what's being said.
I'll take a guess that being a NA native it probably needs colder water then the tropical fish you are keeping it with. Yes it may survive but possibly with a shortened lifespan.
If your water is clean your Oscar is going to grow about 1" a month. There is more to worry about with the oscar in a 55 than just his size, oscar are dirty fish and will polute the water quickly.
I'd suggest you do some reading before aquiring anymore fish, you're already in over your head, and even though you are doing the right thing by posting and asking questions you don't seem to want to listen to what's being said.