Make sure you do big regular water changes and gravel clean the substrate every week.
Clean the filter regularly too otherwise they get hole in the head disease.
Doing a waterchange today, and he is doing absolutely fantastic, he is eating more than ever, and is also gaining my trust, he is now eating baby freeze dried shrimp out of my finger, i'm still testing different foods out with him, to find his likes, and dislikes.
That's great he's doing well. Watch for an ammonia spike in such a new tank. I specifically joined for Oscar advice (kept fish for years but never an Oscar) as I'll be getting one in my new, un-cycled 75G so we are kind of in the same boat minus the fish.
Hey guys, I haven't been on here in a while, but Gargantuan is doing so good, being hyperactive and all, I thank you all for the support, he is a fine fish. I think this will be my last message! Anyways, thank you!
Recently was in the same position a couple of weeks ago. Oscars are known to sulk and be a bit moody especially when the environment is unknown or unstable - give them a few days and theyll start becoming more lively.