Hello,
great job for doing that- it was the right thing. First let me give you some starter points about Oscars.
1. Oscar's are like dogs in many ways. I breed Golden Retriever's, and I breed Oscars, so I know
2. Oscar's will eta, and eat, and never stop eating. They are like dogs. So the major key to a healthy oscar, is food. Oscar's are a big cichlid, and they need food that they can chew. I like the food Hikari Cichlid, but I think Hikari Cichlid Staple is betther. It's the green packet. That is a great starter diet, but ONLY a starter diet. You don't HAVE to feed Oscar's live food, but it does have to be meat. If I have to may guppies I will plop some fry in, I also feed my Oscar's meat that I buy at a store. if you feed your oscar meat for humen's, make sure to wash it for about a half hour- there can be many harmful things on meat. Also, feed beefheart- but only sparingly, as it is fatty and can dirty the water. Big shrimp, like fresh-water Mysis are a hit, and any big, live, food. Also, you can feed basic frozen, freeze-dried, and live food like bloodworms,brine shrimp, daphnia etc.
Remember the Oscar's love there owners, so try and hand feed Osacar. Not at first, wait intill he is used to you. On of my oscar's, Trudy, loves to be stroaked!
2. Oscars, like dogs, need a LOT of space. I think 70 gallon's is find for 0NE oscar, with only a few other fish. If you want some more fish, or more oscars, you are looking 100+ tank sizes. Right now, I have a 500 gallon aquarium with six juvinile oscars- they are loving it.
So, just keep those two factors in mind.
PM me if you need any help
ZOphie