Fisher, who PNE sold to Middlesbrough in January for a reported £300,000 fee, suffered a freak knee injury at home during the summer.
Boro manager Neil Warnock said: "We’re not sure at the moment but it doesn’t look very good,”
"I’ll know tomorrow but it’s looking like an operation and you’re talking nine months so we’re not optimistic about that.
"From what he’s telling us it was a complete accident the way that he did it, with a mate slipping and falling on him and crashing onto his knee.
"It’s the back of his knee.”
Here is a round-up of all the news from the Championship, including the latest transfer talk and gossip.
1. Bournemouth chase Leeds defender
Bournemouth are trying to sign Leeds left-back Leif Davis on a season's loan. (Football Insider) Photo: Bruce Rollinson
2. Lots of interest in former Luton midfielder
Blackburn and Middlesbrough face competition from Turkish side Hatsyspor for Pelly Ruddock who has left Luton after failing to agree a new contract. (Lancashire Telegraph) Photo: Alex Dodd
3. Former Blackburn man set to join Sunderland
Sunderland look set to win the race to sign midfielder Corry Evans, following his release from Blackburn Rovers. (The Athletic) Photo: Press Association
4. Forest striker is a wanted man
Nottingham Forest striker Brennan Johnson, who impressed on loan at Lincoln City last season, is interesting Brentord. (Independant) Photo: Press Association