NFL's Arthur Jones Might Fight UFC ... After NFL Career

Jon Jones might have some brotherly company in the UFC ... 'cause his NFL star sibling Arthur Jones tells TMZ Sports he's considering an MMA career after his football days are over.

Arthur -- a defensive tackle for the Indianapolis Colts -- says he's been training with Jon for years ... and came thiiiis close to taking an MMA fight during the NFL lockout in 2011.

He also happens to be a killer wrestler -- and says he's confident he could hang with pro fighters because he's kicked Jon's ass on several occasions.

Seriously!

So, what does Arthur do to relax? He's a dog breeder who runs Jones Bros Kennels ... where he breeds dogs that are so big, his kids can ride 'em like horses!