I've read a lot saying that it cant be, but it can with some work.
We'll use my Oscar Rusty as an example. Like a lot of people, I got an oscar and a 10g for my first fish setup. Needless to say he had a crappy life for a while. A couple of times he was almost dead, and he developed pretty severe HITH. The picture with the HITH was after it had already started to heal. I just wanted to show what a good varied diet (with no goldfish), adequate filtration, and very very clean water will do. Here is my before and after pictures.

We'll use my Oscar Rusty as an example. Like a lot of people, I got an oscar and a 10g for my first fish setup. Needless to say he had a crappy life for a while. A couple of times he was almost dead, and he developed pretty severe HITH. The picture with the HITH was after it had already started to heal. I just wanted to show what a good varied diet (with no goldfish), adequate filtration, and very very clean water will do. Here is my before and after pictures.

