yeah def wouldnt house an oscar in anything smaller than a 75g, oscars are an especially dirty fish, they are even more dirty than most other fish that grow to their size. and even besides that, oscars get 15-16in and a 55g tank is only 12in wide. how would you like to be kept in a tiny filthy room where you had to struggle to turn around, they just dont comfortably fit in anything smaller due to the dimensions and if you do keep them in something as small as a 37g tank then you would have to be doing multiple large water changes daily in order to keep the water clean enough for them to not get HITH or other illnesses and die and even then they would have no room to swim or move around at all. its not your fault as this is what your lfs people told you and its just another example of how most people working in these stores now nothing about the proper housing requirements of these fish and will tell people anything to make a sale. but luckily you did the smart thing and came on here first. i think you would enjoy keeping a nice convict pair in a 37g tank. you will be able to observe all their personality and even have some kind of schooling dither fish in their with them