My one BP Petey will start a strike soon and it'll last until Feburary or March.
Also have a 4 year old, 1200 gram Mojave that I got in January that hadn't eaten since October. He started eating in July so that's a 9-10 month strike between 2 owners. He now eats his ASFs regularly. :)
Longest I've heard on this forum was 18-24 month food strike.
OP- Watch his weight, if he starts dropping significant weight, then be worried. If he hardly drops anything between meals, he's doing fine. :)