Hmmm... It could be stress or maybe someone used to poke at him in the past while trying to feed him. IDK I'd say, just give him a few days and keep trying to encourage him to eat. After about a week or so if he still refuses to eat, try him slowly on different foods as some bettas can be very picky. If al else fail try live brine shrimp. Let us know if he gets worse though, I'm sure someone here could help you out as well.
I also forgot, keep him quarantined just in case he's sick, especially since you planning on having him in a divided tank.
Last edited by Hisaki Yuki001; 07-08-2011 at 08:15 AM.