Fox News actually probably loves Barack Obama. He is amazingly profitable for them. Their rating are much better since Obama took office.
They promote a conservative agenda by design, and having a president that conflicts with that agenda gives them a lot of material. Their audience tunes in to see the latest thing that Obama has done to wreck the country.
MSNBC benefitted from a similar effect late in Bush's term (once they changed to being more biased towards liberals).