twisted penguin is giving out good information. if i were you, id go buy a good test kit (not strips-they tend to get dampened by moisture in the air every time you use them) and just test your ammonia, nitrItes, and nitrAte levels.. just to see IF you are going through a mini cycle.. if you are, there is nothing you can do but wait.. or run some charcoal to try and remove the odor..i use purigen in my canisters and love it..
if you arent cycling, i would wait a few days, then do another big waterchange. what he said about having 3 oscars is right.. you will probably have two pair up, and the third will get beat to heck and back.. three oscars wont do in a 125 unless they are very docile..
best of luck to ya! i dont think anyone is trying to be mean or criticize you, but alot of us have owned oscars for a looong time and are just trying to tell you what to expect..