How would you know that, you've only had it for 2 weeks. More likely it had settled in and started eating, with the oscars having nothing to do with it. You can do as you like, there are many who have raised them together with no issues. Then there are those who have lost aro in such set ups. So it is whether or not you are willing to take the risk. I'm sure if you loose the aro, you can always buy another at the LFS.
With silver aros it's best to go sooner. Not sure if you realize how fast silvers grow. Yours looks to be 5-6" long, within 6 months it will be 12-15" long. In as short as one years time you'll have a monster on your hands that will be in the 20-24" range.
Oscars like to assert their dominance by bumping and nipping the other fish. If this stresses out your aro he may stop eating. They knock off a few scales here and there. This could lead to infections. Oscars are aggressive and purposely try to keep other fish from eating. Albinos tend not to be as aggressive, however that's usually because they don't see as well.
Seems water changing and salt doesnt workkk! Please help me... He's bottom fins and his fins which we call hands to people are getting worst..... And he's bottom barbel or what ever we call it the other one is getting shorter.. What should i do!? I need to by the marcylyn plus ? Please help me..
What are you readings for ammonia,nitrites,nitrates, and ph? How long has this tank been running and what size and what kind of fish and how many? Fin rot is usually from poor water quality.