Is ONE PIECE episode 455 filler?
Canon No, episode 455 of ONE PIECE is canon.
#455
The Friends' Whereabouts! Revolutionaries and the Gorging Forest's Trap
仲間達の行方 革命軍と暴食の森の罠！
Aired 13 Jun 2010
Mochibayo compiled this list from MyAnimeList's labels, because MyAnimeList's episode data is not reaching us at the moment.