I bought a 55" sony TV used. The picture is really good, but when I watch netflix from my xbox, the picture fades between darker or lighter every minute or so, is there anything I can do to fix this?

If it is only on Netflix through an Xbox it is most likely a refresh rate.issue.

If it is only on Netflix through an Xbox it is most likely a refresh rate.issue.

How can I fix that?

how can i fix that?

Probably can't, refresh rate is built in. Is it OK on straight TV. Google " refresh rate " for explanation.