Oscars usually destroy plants. They like to rearrange the decorations to their liking, not yours.

Anything you put in the tank needs to be sturdy (including heaters!) or your oscar will destroy it. Glass heaters have a tendency to get broken. I suggest you get titanium or stainless steel heaters for your oscar tank. Marineland also makes a very good hard plastic heater. Hikari is much better than a lot of what is available. Omega One and New Life Spectrum brands are considered the best. My oscars get Omega One cichlid pellets, and the tetramin jumbo sticks only because they like them. I wish they would only eat the Omega One. I also try and give them variety like freeze dried or frozen shrimp, and one of these days, I'm gonna try them on homemade to get them to eat a little bit of veggies!